ARTILLERY 
MATERIEL 





BY 



1st Lieut. James P. Kelly F. A 




Class JDi^fcOo 
Book &£_ 



GoEwigtaKLj^ 



COPYRIGHT DEPOSIT. 



FIELD ARTILLERY 
MATERIEL J 



Notes on the Development, 

Use and Care of Modern Field Artillery 

Equipment, Including the 

3" Field Gun, American, French and 
British 75s, the 4.7" Gun, 155mm 
Howitzer, GPF, Fire Control Instru- 
ments, Signal Equipment and small 
arms used by the Field Artillery — 
automatic pistol, automatic rifle and 
the Browning machine gun. 



Compiled by 

JAMES P. KELLY 

1ST LIEUT. FIELD ARTILLERY 

U. S. ARMY 



COPYRIGHT 
BY 

THE UNIVERSITY CO-OPERATIVE STORE 

UNIVERSITY OF MISSOURI 
COLUMBIA, MO. 

I920 



U^pij 



■■■■■- 1 i 



DEDICATION 

To those efficient officers and 
inspiring gentlemen who interested 
the "youngsters" of the Yale bat- 
teries in the service of their coun- 
try, and, in a time of peace, pre- 
pared them for the duties which 
they later performed in a time of 
war, this book is gratefully and 
respectfully dedicated. 



(2) 



,EP 21 1920* 

©CI.A576843 : 



ARTILLERY OF THE FUTURE. 




SELF-PROPELLING CATERPILLAR MARK VII 75-MM. GUN. MODEL 1916. 




SELF-PROPELLING CATERPILLAR MARK II 155-MM. FILLOUX GUN. 



INTRODUCTION. 

The compiler of this volume believes that the Field 
Artillery student should possess a broad, general knowledge 
of the history and development of ordnance, with some idea 
of the elements of gun construction; that he should be ac- 
quainted with the organization, ideals and practicalities of 
modern field artillery armament; that he should know the 
ammunition and the guns in our Field Artillery service with 
their care and maintenance. 

It is also believed that in the R. O. T. C. units of Field 
Artillery the student should make the complete 3" equipment 
the basis of his knowledge of materiel. He should become 
thoroughly and familiarly acquainted with this weapon,, and, 
to a lesser extent, with the other light pieces which are in 
present use. The reason for this being that our experience in 
the World War has shown that a thorough knowledge of one 
class of materiel permits a ready adaptation to any other type. 
He should also know the manner of functioning of the 4.7" 
and 155-mm rifles, with a somewhat more intensive knowledge 
of the 155-mm howitzer — and with a sound knowledge of the 
capabilities and limitations of all. 

To complete his instruction in materiel he should know 
the use and care of Fire Control equipment, Signal equipment, 
and the small arms used in the field artillery, pistol, auto- 
matic rifle and machine gun. 

The lack of a single volume covering the above has been 
the cause of the compilation of this book. The compiler 
hopes the R. O. T. C. student will find in it a text which will 

(3) 



4 FIELD ARTILLERY MATERIEL. 

be interesting, instructive and comprehensive. To the lieu- 
tenants in charge of Department "A" and to those who aspire 
to that responsibility it is hoped that this work will prove a 
valued addition to their professional libraries. 

The subjects covered herein have been taken wholly or 
in part from the various official handbooks, from "Ordnance 
and Gunnery, U. S. M. A.," "Naval Gunnery, U. S. N. A.," 
"America's Munitions," "Gun Making in the U. S. A.," 
"Ordnance and Gunnery for Field Artillery Officers," "Artil- 
lery Firing," "The Field Artillery Journal," Ordnance Doc. 
2033, from lecture notes taken at the School of Fire, Brigade 
Training Pamphlets, and various other sources. 

The compiler is indebted to Lt. Col. Lloyd E. Jones, F. A. 
and Major H. C. Jackson, F. A. for the valuable advice and 
the helpful assistance they rendered in this compilation. 



CONTENTS. 

Page 
Chapters I. Definitions. 11 

II. History and Development of Materiel. 16 

Biblical references — Use by Romans in Punic 
wars — Greeks; Chinese use of pyrotechmy; 
French field artillery in the time of Charles 
VIII; Gustavus Adolphus and artillery in 
the 17th century; Louis XIV; Gribeauval's 
work in 1765; Shrapnel, 1808; Smooth 
bores to rifles, middle of 19th century; 
French "75;" Period 1897 to date. 

III. Elements of Gun Design and Construction. 27 

Guns — wire wrapped and built-up; twist; 
breechblocks; carriages; traversing 
mechanisms ; elevating mechanisms ; 
recoil systems. Air and spring recuper- 
ators; shields; sights; wheels; trails. 

IV. Modern Armament. 46 

Discussions of types of artillery and their 
organization; missions and guns suit- 
able to accomplish different missions; 
ideal and practical types for divisional 
corps and army artillery. 
V. Three-inch Field Gun. 

Weights and dimensions. 62 

Description of gun, carriage, caisson and 
limbers; functioning of principal parts. 

Mounting and dismounting. 

(5) 



FIELD ARTILLERY MATERIEL. 

Page 
VI. 75-mm Model 1897 ("French 75"). 34 

Weights and dimensions. 
Description and functioning of principal 

parts. 
Care, preservation, dismounting. 

VII. 75-mm Model 1916 ("American 75"). 105 

Weights and dimensions. 
Description and functioning of principal 

parts. 
Care, preservation, dismounting, mounting. 

VIII. 75-mm Model 1917 ("British 75"). 147 

Weights and dimensions. 

Description and functioning of prin- 
cipal parts. 

IX. 4.7" Rifle Model 1908. 154 

Weights and dimensions. 
Description and functioning of principal 
parts. 

X. 155-mm Rifle (Filloux Gun) (GPF). 160 

Weights and dimensions. 
Description and functioning of principal 
parts. 

XI. 155-mm Howitzer Model 1918. 167 

Weights and dimensions. 

Description and functioning of principal 

parts. 
Notes on dismounting and mounting — 

cleaning. 



CONTENTS. 7 

Page 
XII. Explosives, Ammunition and Fuzes. 199 

Explosives — classes, fillers, H. E., nitrogen 
compounds. 

Ammunition — classes, discussion of fixed, 
semi-fixed and separate ammunition, 
primers, charges, construction of dif- 
ferent types of shell, care. 

Fuzes — principle of operation, arming, class- 
ification, precautions, tables of fuzes 

giving description, use, etc. 

Ammunition marking. 

XIII. Care and Preservation of Materiel. 236 

Oils and cleaning materials; tools and ac- 
cessories; care and cleaning of different 
parts of carriages, emptying, cleaning 
and filling cylinders, cleaning bore, 
breech, springs, etc.; general instruc- 
tions for care of cloth, leather and 
metal equipment. Cleaning schedules. 

XIV. Fire Control Equipment. 258 

Sights — line, front and rear, panoramic; 
model 1915 and 1917 with their use, 
care and verification. Range Quad- 
rant, care, use and adjustment. B. C. 
Telescope, model 1915 and Aiming 
Circle model 1916, with their use, 
care and adjustment. Range Finder, 
1 meter base, use, care and adjustment. 
Field Glasses. Fuse Setters. 



> FIELD ARTILLERY MATERIEL. 

Page 
XV. Signal Equipment. 285 

Telephones and Monocord Switchboards — 
description, use, adjustments, trouble 
shooting and care. 

Projectors — description, use, adjustment, 
service code for lamps and buzzer, con- 
ventional signals. 

Pyrotechnical signaling, classification of 
rockets, use, code. 

Panels — liason with airplanes, signals, de- 
scription of panels, panel code. 

Flags — classification, use of semaphore and 
wigwag. 

Radio — Description of equipment, SCR-54 
and SCR-54- A Sets, methods of opera- 
tion, use of vacuum detectors, precau- 
tions, sources of trouble, maintenance, 
reception of airplane signals. 
XVI. Small Arms. 315 

Pistol, machine gun and automatic rifle — 
description, use and care. 
XVII. Motors — Reconnaissance car, Dodge, Harley- 328 
Davidson motorcicles. 5- ton tractors, 
ammunition trucks, cargo trucks. How 
to drive, sources of trouble, main- 
tenance. 
Appendices. . 349 

A. Gunner's Examinations — preparations, 
Cannoneers' "Don'ts," training gun 
crews. 

B. Tabular comparison of light guns used 370 
in World War. 

C. Table of Equivalents. 371 
Index. 



LIST OF ILLUSTRATIONS. 



LIST OF ILLUSTRATIONS 

Title Page 

Artillery of the Future Frontispiece 

Diagram Hydro-Springs and Hydro-Pneumatic Recoil Systems 41 

3-inch Field Gun Breech Mechanism Facing 63 

Carriage Model 1902, Plan View Facing 65 

Elevating Gear 67 

Traversing Gear ' . .Facing 66 

Recoil Controlling Mechanism Facing 69 

Caisson Limber, Model 1916 73 

Caisson, Model 1902 Facing 74 

75-mm Field Gun, Model 1897 (French) 85 

Breech Mechanism 86 

Firing Mechanism 88 

Gun Carriage, Longitudinal Section 90 

Gun Carriage, Rear View 91 

Gun Carriage, Left Side 92 

Gun Carriage, Right Side 93 

Gun Carriage, Plan View 94 

Wheel Brake Mechanism (Abatage) 96 

Range Elevating Mechanism 98 

75-mm Field Gun, Model 1916 (American) 107 

Breech Mechanism 108 

Breech Mechanism 109 

Gun Carriage, Left Side 112 

Gun Carriage, Right Side 113 

Gun Carriage, Ear View 116 

Gun Carriage, Plan View 117 

Gun Carriage, Longitudinal and Transversal Sections 119 

Recoil Mechanism 122 

Valve Turning Gear 1Z5 

Angle of Site Mechanism 128 

Elevating Mechanism 130 

Traversing Mechanism 132 

75-mm Field Gun, Model 1917 (British) 148 

Breech Mechanism 149 

Recoil Mechanism 151 

Gun Carriage, Plan View 152 

4.7-inch Gun, Model 1906, Longitudinal Section 155 

Gun Carriage, Left, Plan and Rear Views 158 

155-mm Gun, Model 1918, (GPF) (Filloux) 161 

Longitudinal Section in Battery 163 

Carriage and Limber, Traveling Position Facing 165 

155-mm Howitzer, Model 1918 169 

Carriage and Limber Facing 166 



10 FIELD ARTILLERY MATERIEL. 

Title Page 

Carriage Unlimbered Facing 167 

Breech Mechanism 171 

Breech Mechanism . 172 

Firing Mechanism 174 

Longitudinal Section 180 

Carriage, Left Side 183 

Elevating Mechanism 184 

Traversing Rollers 186 

Traversing Mechanism 188 

Air and Liquid Pumps 190 

Howitzer Carriage, Plan View 191 

Quadrant Sights, Model 1918 193 

DeBange Obturator 205 

Mark II-A Primer 207 

155 Steel Shell Mark IV 210 

155 Shrapnel Mark I. 212 

4.7-inch Gun Ammunition 213 

3-inch Gun Ammunition Facing 214 

Detonating Fuze, Mark III 225 

Detonating Fuze, Mark V 226 

45 Second Combination Fuze, Mark 1 230 

21 Second Combination Fuze, Model 1907 M 231 

75-mm Gun Ammunition 234 

Rear Sight, 3-inch Field Gun ,259 

Panoramic Sight, Model of 1917 261 

Panoramic Sight, Model of 1915 264 

Range Quadrant, 3-inch Field Gun 266 

Battery Commander's Telescope, Model 1915 271 

Aiming Circle 275 

Diagram of Range Finder Principle 279 

Range Finder, Rear View Facing 280 

Range Finder Tripod Facing 281 

Three-Steps in Range Finding Facing 282 

Fuze Setters Facing 284 

Camp Telephone Facing 286 

Diagram Telephone Circuit 287 

Diagram Radio Circuit 307 

The Automatic Pistol, Cal. 45, Model 1911 Facing 316 

Receiver, Barrel and Slide Facing 317 

Component Parts Facing 318 

Component Parts Assembled Facing 319 

Ammunition Truck -. Facing 334 



DEFINITIONS. 11 



CHAPTER I 

DEFINITIONS. 

In the study of any subject which is rather technical in 
nature, it is absolutely essential that the reader be familiar 
with the meaning of the words and phrases which must be 
used in the matter to be discussed. If the subject matter 
is to be understood there must be a common phraseology. The 
reader is therefore strongly urged to perfect his knowledge of 
the following short vocabulary before passing on to the matter 
which follows. 

Ammunition. . A general term applied to all forms of powders, 
shells, cartridges, primers, etc. 

(a) Fixed Ammunition. When the powder charge is en- 
closed in a metallic container which is fixed to the pro- 
jectile, it is called "Fixed Ammunition." 

(b) Semi-Fixed Ammunition. When the charge and metal- 
lic container are a fixed unit but are not fastened to the 
projectile, it is called "Semi-Fixed Ammunition." 

(c) Separate Ammunition. When the powder charge is 
contained in bags separate from the projectile and con- 
taining not a fixed but a varying charge, it is called "Sep- 
arate Ammunition." 

Artillery. All firearms not carried by hand, excepting ma- 
chine guns. It is divided into two general classifications: 
(1) artillery of position, and (2) mobile artillery. 
(1) Artillery of Position is that which is permanently 
mounted in fortifications. 



12 FIELD ARTILLERY MATERIEL. 

(2) Mobile Artillery consists of two classes: first, artillery 
designed to accompany an army in the field; second, 
railway artillery which requires tracks for its transporta- 
tion. 

Ballistics. The science of hurling projectiles or of the motion 
of projectiles in their flight. 

Bore. The hole which extends from the muzzle to the breech. 
The passageway for the projectile. That part of the 
tube which is bored out. 

Breech. The rear end of the gun, tube, or barrel. 

Caisson. A two-wheeled vehicle which supports an ammuni- 
tion chest. The wheeled equipment of a gun section 
consists of one gun with its limber and one caisson with 
its limber. For a caisson section it consists of two cais- 
sons with their limbers. 

Caliber (Calibre). The diameter between the highest points 

in the bore. 
Carriage, gun. Usually understood to mean all the piece 

except the tube with its appurtenances and the limber. 

Cartridge case. A hollow cylinder shaped to fit the bore. A 
container for the propelling charge. 

Charge. 

(a) Propelling. A quantity of powder used in the bore to 
generate the gases which propel the projectile from the 
gun. 

(b) Bursting. A quantity of powder used in shrapnel to 
strip off the head of the projectile and to force out the 
balls. 

(c) Explosive. The matter used in a shell to detonate it 
at the end of its flight. 

Cradle. In general, that part of the carriage which houses the 
recoil and counter-recoil mechanisms. 



DEFINITIONS. 13 

Elevating Mechanism. The device used to elevate the gun 
through a vertical arc in order to give the gun an eleva- 
tion corresponding to the desired range at which the 
piece is to be fired. 

Fire Control Equipment. Those instruments used to compute 
firing data, observe and correct the fire, such as B. C. 
Telescopes, Aiming Circles, Range Finders, etc. 

Firing Mechanism. A device located in the breechblock for 
exploding the primer and thus causing the ignition of the 
powder charge. 

Fuze. That part of the round which is fastened to the point or 
to the base of the projectile and causes the latter to be 
detonated or exploded near the time or the place desired. 

Fuze Setter. A device used to set time fuzes in such a manner 
that shrapnel or shell will burst at or near the desired 
height in air. 

Gun. A metallic tube from which projectiles are hurled 
by gases generated from the ignited powder. In general, 
all fire arms; but in Field Artillery terms, comparatively 
long-barreled weapons using relatively high muzzle 
velocity in contra-distinction to the howitzers and mor- 
tars. 

Howitzer. A weapon which differs from a gun in that for 
the same caliber it uses a shorter tube, lower muzzle 
velocity and generally a more curved trajectory. From 
two to seven varying strengths of propelling charges may 
be used in the howitzer. This gives it selective angles of 
fall, and allows the howitzer to reach targets that are 
hidden from the flat trajectories of guns. 

Initial Velocity. The speed with which the projectile first 
moves. 



14 FIELD ARTILLERY MATERIEL. 

Limber. A two-wheeled carriage which is sometimes used 
to carry an ammunition chest and always used to support 
the weight of the trail of the piece or caisson. It adds 
the other two wheels to make a four-wheeled vehicle. 

Materiel. A term used in the Field Artillery in contra-dis- 
tinction to Personnel. 

Mortar. A weapon using for the same caliber, a barrel much 
shorter than the corresponding howitzer. Used at short 
ranges with extreme steep angles of fall to reach highly 
defiladed targets. 

Muzzle. The front end of the bore. 

Muzzle Velocity. Speed or velocity of the projectile measured 
as it leaves the muzzle. 

Ogive. The rounded shoulder of the projectile. 

Ordnance. Arms, ammunition, and their accessories. 

Piece. A fire arm, small or large. 

Primer. Device used to insure ignition of the propelling 
charge. 

Projectile. The effect-producing part of the round. The 
bullet-like form which is thrown toward the target. 

Quadrant, gunners. A device for measuring angles of eleva- 
tion. 

Recoil Mechanism. That part of the piece which checks the 
recoil — or kick — that always occurs when a piece is 
fired. It generally includes the counter-recoil mechan- 
ism which restores the tube "into battery" after it has 
fired. 

Rifle. A gun. A weapon with a comparatively long barrel 
and high muzzle velocity. Rifles under 6 inches seldom 
use over two different charges. Term used in contrast 
to Howitzer or Mortar. 



DEFINITIONS. 15 

Rifling. The lands and grooves in the bore of the piece which 
imparts to the projectile during its passage through the 
bore, the rotary motion that increases accuracy and range. 

Round. Consists of the primer, cartridge case or powder 
bags, projectile and fuze. For light Field Artillery the 
round weighs about 18 lbs and the projectile about 15. 

Shell. A projectile which secures its effect by the force of its 
detonation, the bursting of its walls, and the fragmenta- 
tion and velocity of the fragments. Also used as a gas 
carrier. 

Shrapnel. A projectile which secures its effect by the expul- 
sion in the air of lead balls with shot-gun like effect. 

Trail. That part of the piece which extends from the axle 
to the rear and transmits the force of recoil to the ground 
through the trail spade. Usually supports the elevating 
and traversing mechanisms. 

Traversing Mechanism. A device used to give the piece 
direction by moving it through a horizontal arc. 



16 FIELD ARTILLERY MATERIEL. 



CHAPTER II 
HISTORY AND DEVELOPMENT OF MATERIEL. 

In taking up the study of materiel, the Field Artillery 
student should know something of the history and develop- 
ment of ordnance and the reasons for the various changes 
which have taken place from time to time. 

The sole use of a gun is to throw a projectile. The earliest 
projectile was a stone thrown by the hand and arm of man- 
either in an attack upon an enemy or upon a beast that was 
being hunted for food. Both of these uses of thrown projec- 
tiles persist to this day, and, during all time, from prehistoric 
days until the present, every man who has had a missile to 
throw has steadily sought for a longer range and a heavier 
projectile. 

In ancient times the man who could throw the heaviest 
stone the longest distance was the most powerfully armed. 
During the Biblical battle between David and Goliath, the 
arm of David was strengthened and lengthened by a leather 
sling of a very simple construction. Much practice had given 
the youthful shepherd muscular strength and direction, and 
his stronger arm and straighter aim gave him power to over- 
come his more heavily armed adversary. 

Projectile- throwing machines were developed after the 
fashion of a crossbow mounted upon a small wooden carriage 
which usually was a hollowed trough open on top and upon 
which a stone was laid. The thong of the crossbow was drawn 
by a powerful screw operated by man power, and the cross- 
bow arrangement when released would throw a stone weighing 
many pounds quite a distance over the walls of a beseiged 
city or from such wall into the camps or ranks of the besiegers. 



HISTORY AND DEVELOPMENT OF MATERIEL. 17 

This again was an attempt by mechanical means to develop 
and strengthen and lengthen the stroke of the arm and the 
weight of the projectile. The Bible states that King Usia 
(809-757 B. C.) placed types of artillery on the walls of Jeru- 
salem. The Romans used it in the Punic Wars. The Alexan- 
drian technicians established scientific rules for the construc- 
tion of early weapons. Athenaeus reports catapults having 
a range of 656 meters and that the gigantic siege tower at 
Rhodes successfully resisted stone projectiles weighing 176 
pounds. 

References to explosives are to be found in works as old 
as Moses. Archimedes is said by Plutarch to have "cast huge 
stones from his machines with a great noise;" Caligua is said 
by Dion Cassius to have had machines which "imitated 
thunder and lightning and emitted stones;" and Marcus 
Graecus in the eighth century gives a receipt of one pound of 
sulphur, two of willow charcoal and six of saltpetre, for the 
discharge of what we should call a rocket. 

The use of Greek fire was understood as early as the sixth 
century, but powder was earliest used in China, perhaps a 
thousand years before Christ, and was introduced to European 
notice by the Saracens. 

From the discovery of gunpowder by the English monk 
Bacon in 1248, sixty-five years elapsed before a Franciscan 
monk produced the first gun in Germany, about 1313. The 
first guns were of a small breech-loading type, supported in 
front by crossed sticks and anchored by a spike at the breech. 
Later these guns were fastened to cradles, the latter being 
mounted on sleighs, and finally, in 1376, the Venetians pro- 
duced the first wheel mounts, which had become common by 
1453, when the Turks took Constantinople. 

The ancient carriages were remarkable because of the 
fact that in general design they embodied the same principals 
which are included in the field carriages of today. One ex- 

T. B.— 2 



18 FIELD ARTILLERY MATERIEL. 

ample from the fifteenth century shows a breech-loading 
gun mounted in a cradle supported by trunnions on the for- 
ward extension of the trail over the axle. The cradle was 
elevated by a pin-and-arc arrangement, supported on the trail. 
The axle supported by wheels passes through the trail to the 
rear of and below the cradle trunnion support and in front of 
the point of attachment of the elevating arc. 

Field guns fell into disuse about 1525 with the intro- 
duction of musketry, and remained so until 1631, when Gus- 
tavus Adolphus gave artillery its true position on the battle- 
field. 

Swedish artillery reigned supreme in the early part of the 
seventeenth deritury. Gustavus introduced marked changes 
by making the guns and the carriages lighter and handier, 
and by adapting their movements to those of the other arms 
and to the requirements of the battlefield. In this, as in all 
his military efforts, his motto was mobility and rapidity of 
fire. 

In 1624 Gustavus had all his old types of guns recast into 
newer models and the following year he himself contrived a 
gun which three men and one horse could maneuvre to good 
effect. It was an iron three and four pounder with a cartridge 
weighing less than a pound and consisting of a charge held in 
a thin wooden case wired to a ball. This was the first artillery 
cartridge, the original fixed ammunition. The gun was after- 
wards used in other European armies and known as the "piece 
Suedoise." Not only had it the advantage of lesser weight 
but its cartridge was always ready to fire and it could be 
fired eight times to the six times of the infantry musket of 
that day. 

In the wars against the Poles, Gustavus employed with 
profit the so-called leather cannon, a fact which shows how 
lacking the times were in artillery power. These guns were 
invented in the early 1620s by a Colonel Wurmbrandt, and 



HISTORY AND DEVELOPMENT OF MATERIEL. 19 

consisted of a thin copper tube reinforced by iron bands and 
rings, then bound with rope set in cement, the whole covered 
with sole leather. The tube was made to screw in and out 
because it grew heated by from eight to twelve charges and 
had to be cooled. The gun carriage was made of two planks 
of oak. The gun without the carriage weighed about ninety 
pounds and was fired with a light charge. They were used 
during 1628-29 and then gave way for four pounder cast-iron 
guns which remained in common usage in Europe until artil- 
lery was reorganized by Frederick. 

Gustavus' batteries excited universal admiration. Grape 
and canister were generally employed in the field guns and 
round shot only in the siege guns. Artillery was used massed 
or in groups and also- with regiments of foot soldiers. Gus- 
tavus was probably the first to demonstrate the real capabil- 
ities of artillery. 

Mortars throwing bombs were first used at the siege of 
Lamotte in 1634. Hand grenades, shells, fire-balls, etc., 
came into more general use as the German chemists made their 
new discoveries. Artillery practice grew to be something of 
a science; experts took it up and the troops were better in- 
structed. Regimental artillery, that is* artillery with the in- 
fantry, was attended by grenadiers detailed for the work. 
There were special companies for serving the reserve guns. 

The period following the Thirty Years' War — the middle 
of the seventeenth century — gave no great improvement to 
the art of war but there were many marked advances in the 
matter of details of construction. During the era of Gustavus 
it was Sweden that led in making war more modern; during 
the era of Louis XIV it was France. 

Artillery ceased to be a guild of cannoneers as it long had 
been and became an inherent part of the army. More intel- 
ligence was devoted to it and more money spent on this arm 
of the service; it grew in strength and importance, and was 



20 FIELD ARTILLERY MATERIEL. 

markedly improved. But while the artillery service ceased 
to be a mere trade, it did not put on the dignity of a separate 
arm, nor was the artillery of any great utility in the field until 
well along in the eighteenth century. Guns, however, in 
imitation of the Swedes, were lightened, particularly so in 
France; powder was gradually compounded on better receipes; 
gun-metal was improved; paper and linen cartridges were in- 
troduced; gun carriages were provided with an aiming wedge; 
and -many new styles of guns and mortars, and ammunition 
for them were invented. 

Science lent its aid to practical men, and not only ex- 
hausted chemical ingenuity in preparing powder and metal, but 
mathematical formulas were made for the artilleryman, and 
value of ricochet firing was discovered. Louis XIV founded 
several artillery schools, and initiated the construction of 
many arsenals. Fontainebleau, the French artillery school 
which trained many Americans during the World War had 
its beginning in this period. Finally, the artillery was or- 
ganized on a battery and a regimental basis, and careful 
rules were made for the tactics of the guns. These were 
served by dismounted men and generally hauled by contract 
horses. 

Although sensibly improved, the artillery was far from 
being skillfully managed and was slow firing; it usually stood 
in small bodies all along the line of battle. It was heavy and 
hard to handle and haul, principally because the same guns 
were used for both siege and field work, and was far from being, 
even relatively to the other arms, the weapon which it is to- 
day. 

In 1765 General Gribeauval of France introduced artillery 
improvements, especially in the carriages, and formed a dis- 
tinct artillery service for the field which was lighter than the 
old service and was drawn by teams which were harnessed 
double as they are to-day. 



HISTORY AND DEVELOPMENT OF MATERIEL. 21 

Howitzers were introduced in France in 1749. The weap- 
ons were given an early sort of perfection by the Dutch. 
The term "howitzer" comes from the German "haubitz." 
In 1808 the first shrapnel appeared at Vimera. It was in- 
vented by an English colonel by the name of Shrapnel. At 
the time it was known as case shot. The type employed by 
Napoleon, had a fuze that could be used at two different 
ranges. The French still have this type in their armament. 

Field artillery now began to appear in the form which it 
was to retain with but a few changes, until the era of the mod- 
ern field carriage. The cradle disappeared, muzzle-loading 
guns cast with trunnions taking its place, and a stepped wedge 
resting on the trail superseded the pin and arc. With the 
exception of the gun, most parts of these carriages were of 
wood and were to remain so until 1870, when metal carriages 
came into general use. Muzzle loading guns had supplanted 
breech-loaders because of the poor obturation and the many 
accidents resulting from use of the latter type. Although 
numerous experiments were made, breech-loading guns did 
not come into vogue again until 1850, when the experiments 
of Major Cavalli (1845), the Walnendorff gun (1846) and 
the Armstrong gun (1854), produced satisfactory types. 

Up to 1860 practically all guns were smooth bore. Even 
during the Civil War the smooth bore was generally used, 
although the rifled gun began to make an appearance and 
was used in small numbers by both sides at the battle of 
Gettysburg. Some breech loaders began to appear at the 
same time. Improvement in the ballistic properties of the 
gun necessitated a corresponding improvement in the sighting 
facilities. In 1880 rifled breech loading and built-up steel 
cannon came into general use. Rifled guns shoot accurately 
and as a result, improved methods in direct laying were de- 
vised. 



22 FIELD ARTILLERY MATERIEL. 

The period between from 1880 to the present, has brought 
about changes in gun construction which, possibly, have been 
equaled in importance to artillery only by the present change 
which is taking place in the means of artillery transportation 
and self-propelling mounts. In this period in rapid succession 
came the modern breechblock and with it the rapid firing gun. 
This brought about the change to the present system of break- 
ing the force of recoil of the gun and restoring it to its firing 
position without disturbing the position of the carriage. This 
added to the possibilities of rapid and more accurate fire. 
Then came the invention and use in the field artillery of 
smokeless powder. Previous to this time the great amount 
of smoke produced by the black powder when the piece was 
fired retarded the rapidity of fire because it enveloped the 
materiel in a thick cloud of smoke which obscured the target 
and made it impossible to fire again until the smoke had blown 
away. It made concealed positions for the artillery almost 
impossible. The advent of smokeless powder made firing 
more rapid and made possible the selection of concealed 
positions. This in turn made indirect fire feasible and neces- 
sitated the development of better sights. Indirect fire in- 
creased the rapidity of fire and gave to the commanders of 
firing units a greater control over their fire. With the use of 
recoil mechanisms and shields for the guns, the cannoneers 
were permitted to serve the piece continuously — a condition 
which was impossible with the recoiling carriage. The shields 
made it almost impossible to put the gun out of action unless 
some vital part of the mechanism was destroyed. 

The first of the modern carriages which were produced 
in the early nineties should be classified as semi-rapid car- 
riages, as the recoil brakes were so abrupt that the carriage 
was not stable and jumped considerably, gaining for the type 
the sobriquet of "grass-hopper guns." 



HISTORY AND DEVELOPMENT OF MATERIEL. 23 

In 1897 the immortal French "75" was born, the pioneer 
of all modern quick-firing field guns, which still maintains 
its superiority in many respects over later designs. 

In 1902 our own 3-inch field gun was produced and still 
finds favor among many of our field artillery officers, even over 
the French '75." 

The Deport carriage brought to this country from Italy, 
in 1912, introduced to us the split trail, high angle of fire, 
wide traversing type of field gun carriage. This carriage 
was extensively tested by the Ordnance Department; by the 
Field Artillery Board at Fort Riley, Kansas; and by the School 
of Fire for Field Artillery, at Fort Sill, Oklahoma. The 
Field Artillery Board unqualifiedly approved of the Deport 
carriage and recommended that it be adopted. The School 
of Fire for Field Artillery also approved of this type. 

In 1916 the United States produced a 75-mm field gun 
which featured a split trail with an elevation of 57 degrees 
which permits its use as an anti-aircraft weapon and a variable 
length of recoil which prevents the breech from hitting the 
ground at the extreme elevations. It has a traverse of 800 
mils in comparison to the 106 of the French 75 and the 142 
and 140 of the British 75 and American three-inch field gun. 

The outbreak of the late war saw all modern armies 
largely equipped with guns resembling the French "75" 
in a long-run recoil mechanism, weight of projectile and weight 
of carriage, etc. The fact that the largest number of horses 
which could best be handled to manuever the light guns — 
about 6 — could not pull over a long period a gun or caisson 
with its limber if the weight was more than about 4500 pounds, 
resulted in the practical standardization of light guns in all 
armies. So in 1914 we see that time and development had 
given light gun perfection and mastery of artillery technique 
to the French while the Germans, probably, possessed the most 
efficient artillery program. The German types of weapons 



24 FIELD ARTILLERY MATERIEL. 

were more varied and perhaps better suited to the varying 
artillery needs in rendering that assistance to the infantry 
for which the artillery exists. 

In our service during the World War, French 75s and the 
155-mm Howitzer were used as divisional artillery. Two 
regiments of the light guns and one regiment of 155-Howitzers 
were assigned to each infantry division. As the war progressed 
guns and howitzers ranging from the 4.7 r/ rifle, up to, and in- 
cluding 14 and even 16-inch naval guns on railroad mounts, 
were used as Corps and Army artillery. 

Thus artillery development has gone steadily forward. 
Every military power has striven with the aid of its best 
engineers, designers and manufacturers to get a stronger 
gun, either with or without a heavier projectile, but in every 
case striving for greater power. As a special development 
and a not too important one, due to its lack of effectiveness in 
comparison to its cost, we fined the now famous long range 
gun of the Germans, successfully delivered a projectile ap- 
proximately 9 inches in diameter into Paris punctually every 
twenty minutes from a point about 75 miles distant. The 
Germans used three of these guns in shelling Paris. Their 
life was probably limited to about 75 rounds due to the ex- 
cessive demands made upon the materiel. 

The American Field Artillery Service now has before it 
four types of field gun carriages, namely our 3 r/ model of 1902; 
the French 75 M-1897; the British 18 pounder, M-1905 con- 
verted to a 75-mm (known as the model of 1917); and our 
75-mm model, 1916. There is being produced (1919-20) 
an improved model of 1916 75-mm carriage on which the St. 
Chamond pneumatic recuperator, adopted jointly by the 
American and French governments, will be substituted for the 
spring recuperators; and the French 75-mm gun will be sub- 
stituted for our shorter calibered type. From these types one 
must be selected. An intelligent selection involves a con- 



HISTORY AND DEVELOPMENT OF MATERIEL. 25 

sideration of what may be expected in the future in order that 
it may best fit in with the new types yet to be evolved. 

For horsed artillery — and horse artillery will be with us 
for some years to come — the limiting features of draft and 
man power will still pertain. 

For tractor-drawn mobile artillery, the limiting feature 
is the tractive power of the tractor with relation to the weight 
of the gun and carriage, the unit being physically limited in 
weight by the supporting — power of the pontoon bridge which 
is about 10,000 pounds per vehicle. 

For Caterpillar Artillery. — By that is meant guns 
mounted on caterpillar tractors — the limiting features are 
power and weight, coupled with the weight limitations of the 
pontoon bridge. To circumvent the question of weight, the 
load may be divided by mounting the motor by an electric 
generator on one caterpillar and the gun with an electric 
motor, on the other, a transmission cable connecting the two 
vehicles. 

In conclusion it might be said that one of the greatest 
changes which has ever taken place in the development of 
field artillery is now underway in the form of motorization. 
Prior to 1917 horse traction had been the sole means of trans- 
porting mobile field artillery. The limit of the capabilities 
of horse traction placed a weight limit upon gun construction 
and to some extent upon artillery tactics. The increase in 
the ratio of field artillery to infantry, the corresponding de- 
mand for artillery types of horses and the decrease in the 
availability of the latter as the war continued, combined with 
the great improvements which were constantly being wrought 
in mechanical transportation as the war lengthened, opened 
the way for artillery motorization. 

The French began by placing their 75s on trucks for 
rapid changes of position. All the armies saw the possible 
advantages to be gained from the use of trucks with artillery 



26 FIELD ARTILLERY MATERIEL. 

but none planned — nor have any since put into practice — the 
extensive use of trucks, caterpillar tractors and motor trans- 
portation for personnel, which the United States planned on 
her entrance into the war. It was planned to equip about one- 
third of the A. E. F. artillery regiments with complete motor 
equipment. This plan did not entirely materialize but after 
the armistice the 3rd Field Artillery Brigade of the 3rd 
Division was completely motorized and its practice marches 
in Germany were most successful and full of promise for the 
future. To date the motorization of all our mobile Field 
Artillery, with the exception of about fifty per cent of the 
light field guns, has been authorized. 

Motor traction gives a better performance than animal. 
While the latter, especially with the light field guns, possesses 
great mobility, it is not a sustained nor a persistent mobility; 
it is more easily exhausted and requires longer to recuperate. 
These are points of vital importance from a military viewpoint. 

In 1920 a self-propelling caterpillar mounted with a 75- 
mm gun, model 1916, was tested with a view to ascertaining 
the ability of the motor to function in water, i. e. fording 
streams, etc. The caterpillar successfully moved through 
ice water which completely submerged the carburetor. 

Passenger cars for the transportation of personnel, four 
wheel drive trucks with caterpillar tractors for the transporta- 
tion of the materiel, and the development of self-propelling 
mounts for the 75 and 155 rifles are the latest and the most 
important developments in field artillery materiel. 



ELEMENTS OF GUN CONSTRUCTION AND DESIGN. 27 



CHAPTER III 

ELEMENTS OF GUN CONSTRUCTION AND DESIGN 

"A gun is a machine by which the force of expanding gas 
is utilized for the purpose of propelling a projectile in a defi- 
nite direction." It is essentially a metal tube closed at one 
end, of sufficient strength to resist the pressure of the gases 
caused by the combustion of the powder charge in the con- 
fined space at the closed end of the tube behind the projectile. 
The rapid combustion of the powder, which produces a high 
temperature, gives rise to a pressure uniformly exerted in all 
directions within the confined space. The energy exerted is 
used in forcing the projectile from the tube. 

TUBES 

Due to the effort of the large amount of superheated 
gas generated, which tends to expand in all directions, tre- 
mendous rending stresses are set up in the tube. Formerly 
these stresses were met by a sheer mass of metal, but, as the 
size of the projectiles increased and the necessary pressure to 
give them muzzle velocity increased, the size of the guns in- 
creased beyond the practical limits of mobility. This was at first 
offset by forgings of refined alloyed steels, but even these failed 
to keep pace with the increasing pressure desired. The new 
condition was met by the introduction of the "built-up" and 
the "wire-wrapped" guns. The modern built-up gun is 
made by assembling one or more superimposed cylinders 
around a central tube. The superimposed cylinders, whose 
inside dimensions are slightly smaller than the outside dimen- 
sions of those on which they are to be assembled, are expanded 
by heat sufficiently to allow them to be assembled over the 



28 FIELD ARTILLERY MATERIEL. 

tube. The subsequent contraction on cooling causes each 
of them to exert a uniform pressure on the cylinder immedi- 
ately underneath. This method of assembling is called 
"shrinkage." This gives a compression to the inner tube and 
a slight tension to the outer one. The compression is so 
much additional strength to the tube because it must first be 
overcome before the powder gases can exert a tension on the 
inner tube fibers. The exact amount of the compression and 
tension for all parts of a gun at rest or resisting an explosion 
is a matter of mathematical calculation. The built-up con- 
struction has been used in practically all our present day types 
of field artillery. 

THE WIRE-WRAPPED GUN. 

Wire-wrapped guns consist of: 

(a) An inner steel tube which forms a support on which 
the wire is wrapped and in which the rifling grooves are cut. 

(b) Layers of wire wrapped upon the tube to increase 
its resistance by the application of an exterior pressure as well 
as to add to the strength of the structure by their own resist- 
ance to extension under fire. 

(c) One or more layers consisting of a steel jacket and 
hoops placed over the wire with or without shrinkage. The 
jacket generally furnishes longitudinal strength to the guns, 
and the breech block is screwed into the jacket, or into a 
breech bushing, which is screwed into the jacket. 

The principal advantages of this type of gun over the 
built-up is economy of manufacture and greater facilities for 
inspection of materiel in the layers over the tube. The wire 
wrapping has itself a large reserve of strength due to the high 
elastic limits that may be given it. Two methods are used to 
wrap the wire: (a) at constant tension (b) at varying tension 
so that when the gun is fired with the prescribed pressure, 



ELEMENTS OF GUN CONSTRUCTION AND DESIGN. 29 

all layers of wire shall be subjected to the same tangential 
stress. The latter method is theoretically better, but be- 
cause of the ease of manufacture, together with the large 
factor of safety possible, the wire is usually wrapped at a 
constant pressure. 

THE BUILT-UP GUN. 

All army guns except small howitzers or mortars are of 
the built-up or wire- wrapped type. Built up guns of less than 
5" caliber, or howitzers up to 8" caliber consist of an inner 
tube and a jacket shrunk onto this tube. The jacket covers 
the breech end of the gun and extends forward to the center 
of gravity. Built-up guns of larger caliber have one more 
layer of hoops in addition to the jacket, one layer of hoops 
usually extending to the muzzle. 

The bore of the tube forms the powder chamber, the seat 
for the projectile and the rifled bore. Rifling consists of a 
number of helical grooves cut in the surface of the bore. The 
soft metal of the rotating band of the projectile is forced into 
these grooves causing the projectile to take up a rotary motion 
as it passes through the bore. This is necessary in order to 
keep the projectile stable in its flight. 

TWIST. 

By twist of rifling is meant the inclination of one of the 
grooves to the element of the bore at any point. Rifling is 
of two kinds: (a) Uniform twist, or that in which the twist 
is constant throughout the bore, (b) Increasing twist or 
that in which the twist increases from the breech towards the 
muzzle. 

The twist of rifling is usually expressed in the number of 
calibers length of bore in wdiich it makes one complete turn. 
The twist actually required at the muzzle to maintain the 



30 FIELD ARTILLERY MATERIEL. 

stability of the projectile varies with the kind of projectile 
and the muzzle velocity. If a uniform twist be used, the 
driving force on the rotating band will be at a maximum when 
the pressure in the guns is at a maximum — or near the origin 
of rifling (seat of the projectile). The increasing twist 
serves to reduce the maximum driving force on the band thus 
lessening the danger of stripping the band. This is its prin- 
cipal advantage over the uniform twist, though it also reduces 
slightly the maximum pressure in the gun. The principal 
disadvantage of the increasing twist is the continued change 
in form of the grooves pressed in the rotating band, as the pro- 
jectile passes through the bore. This results in increased 
friction and a higher value for the passive resistance than with 
a uniform twist. (Note: greater ranges obtained by cutting 
grooves in projectile, principal used on the long range gun by 
the Germans.) If the twist increases from zero at the breech 
uniformly to the muzzle, the rate of change in the tangent to 
the groove is constant. A twist in this form offers less resist- 
ance than the uniform twist to the initial rotation of the pro- 
jectile. To still further diminish this resistance a twist that 
is at first less rapid than the uniformly increasing twist and 
later more rapid has been generally adopted for rifled guns. 
Formerly in our service the twist was uniform; one turn 
in 25 calibres for guns and one turn in 20 calibres for howitzers. 
All the latest model army guns, however, have an increasing 
twist of one turn in 50 calibres at the breech to one turn in 
25 calibres at a point from 2 to 4 calibres from the muzzle. 
In howitzers and mortars the twist is sometimes one turn in 
40 calibres at the breech to one turn in 20 calibres at a point 
several calibres from the muzzle. Some mortars are rifled 
with a uniform twist and some guns have a rifling which begins 
with a zero twist. (The 1905 3" gun, to 1 in 25.) 



ELEMENTS OF GUN CONSTRUCTION AND DESIGN. 31 

OUTER CYLINDERS. 

Outside of the tube is the jacket. It extends to the rear 
of the tube a sufficient distance to allow of seating the breech 
block. In this manner the longitudinal stress due to the pres- 
sure of the powder gases on the face of the breech block is 
transmitted to the jacket thus relieving the metal of the tube 
from this stress. In all built-up guns there is some method 
devised for locking the tube to the jacket so as to prevent rela- 
tive movement of these parts. 

Considering the gun alone the greatest range is obtained 
at an angle of about 43 degrees from that gun which fires 
the heaviest projectile with the greatest velocity. The caliber 
being limited to from 2.95 inch to 3.3 inch, the projectile is 
limited in weight to from 12 to 18 pounds. The weight of the 
gun is limited to between 700 and 1000 pounds and in length 
to between 27 and 36 calibers. The longer the gun, the greater 
the weight and velocity from the same charge of powder. 
A pressure of 33,000 pounds per square inch with a corres- 
ponding velocity of 1700 f. s. has been found to be as high a 
pressure and velocity as are desirable for a reasonable length 
of life for a field gun, the average life of which is 10,000 ac- 
curate rounds. 

Under the French school of artillery, which dominates 
our service at present, our bore is 75-mm, the weight of our 
shell 12 pounds, our shrapnel 16 pounds, the velocity for the 
one about 1,750 f. s. and for the other about 1,680 f. s. 

BREECHBLOCKS. 

The breechblock appears in four distinct types. Our 
own service has for years used the swinging interrupted screw 
breechblock which in the 1905 model is the equal of any of 
that type in existence. The swinging block has serious 
disadvantages for high angle fire in that it requires an ex- 



32 FIELD ARTILLERY MATERIEL. 

cessive amount of room to operate and is difficult to load at 
high elevations. 

The Italians have introduced a new breechblock in one 
of their recent guns, consisting of a half cylinder with super- 
imposed spherical face on its cylindrical surface rotating ver- 
tically about a horizontal axis perpendicular to the axis of 
the bore. The gun is loaded through a groove in the breech- 
block when the latter is in its horizontal position. The block, 
which is semi-automatic, is very satisfactory. It is adapted 
to high angle fire. 

The French in their "75" have used the rotating eccentric 
screw type, which is rapid in movement and lends itself fairly 
well to high angle fire. It is completely enclosed and of 
rugged construction. 

The Germans have used the sliding wedge type of block, 
moving in a horizontal direction, which does not lend itself 
to high angle fire. 

The United States in its recent field carriage adopted the 
sliding wedge type in a vertical plane on account of its mani- 
fest superiority in fire at high angles. This block is rather 
difficult to manufacture and the type has a tendency to stick. 
The automatic closing necessitates a strong closing spring 
which fatigues the block operator, No. 1 in the gun squad. 
It is interesting to note that in a prospective new design for 
the 1916 gun carriage the American Ordnance Department 
adopted the French breechblock; and the St. Chamond Com- 
pany, designing for the American Expeditionary Forces, 
adopted the American drop block. 

Requirements for a breech mechanism : 

The following may be said to be the principal require- 
ments for a successful breech mechanism. 

1. Safety. To be safe: (a) the gas must be restrained 
from escaping to the rear; this sealing or obturation must be 
automatic, greater pressure insuring better obturation, (b) 



ELEMENTS OF GUN CONSTRUCTION AND DESIGN. 33 

The breech of the gun must not be weakened by the fitting 
of the breech mechanism, (c) The parts must have ample 
strength to prevent any portion from being blown to the rear. 

(d) The danger of premature discharge must be minimized. 

(e) The breechblock must be securely locked to prevent 
opening on firing. 

2. Ease and Rapidity of Working. Otherwise, rapid 
and continuous fire cannot be maintained. Hence this would 
include facility in loading and certainty of extraction for 
rapid fire guns. 

8. Not Easily Put Out of Order. In other words it 
must be able to meet service conditions and hard usage. Parts 
should have a reserve strength. 

4- Ease of Repair. Parts most exposed to wear should 
be so designed as to permit being replaced. This will also 
include accessibility to parts, so that breakage of a part will 
not disable the mechanism for a long time. 

5. Inter changeability. Not only should individual parts 
be made interchangeable by accurate workmanship, but the 
whole mechanism should be capable of being mounted on 
similar guns. This is to meet service conditions. 

GUN CARRIAGES. 

A modern gun carriage is expected to stand steady on 
firing, so that in the first place it requires no running up, 
and in the second place it maintains the direction of the gun 
so that only a slight correction in elevation and direction is 
required after each round. The carriage is maintained in 
position by the spade, which sinks into the ground, and by the 
friction of the wheels upon the ground. If the force of the 
recoiling gun were communicated directly to the anchored 
carriage the effect would be to make it jump violently, which 
would not only disturb the lay, but would prevent the can- 
noneers from maintaining their position. The hydraulic re- 

T. B.— 3 



34 FIELD ARTILLERY MATERIEL. 

coil brake is therefore interposed between gun and carriage. 
If the guns were rigidily attached to the carriage the latter 
would be forced back a short distance at each round, and the 
whole of the recoil energy would have to be absorbed in that 
short motion. Instead of this the gun alone is allowed to 
recoil several feet and although the recoil energy is in this 
case greater than it would be if gun and carriage recoiled 
together yet it is so gradually communicated to the carriage 
that instead of a violent jerk we have a steady, uniform 
pull, the only effect of which is to slightly compress the earth 
behind the spade. In a well designed carriage the amount of 
this pull is always less than that required to lift the wheels 
off the ground by rotating the carriage about the spade. 

The only motion of the carriage which takes place is that 
due to the elastic bending and rebound of its parts under the 
cross strains set up on discharge. These strains are inevitable 
since the direction of recoil cannot be always exactly in the 
line of the resistance of the earth behind the spade. This 
movement of the axis is known as jump and must be deter- 
mined by experiment for the individual piece in its particular 
mounting. 

The principal parts of the typical gun carnage are the 
cradle, a device for mounting the cradle — called in the different 
models rocker, pintle yoke, and top carriage, the trail, the 
wheels and axle. The gun slides in recoil on the upper surface 
of the cradle and the cradle contains the recoil controlling 
parts. 

In the design of the carriage the constructional difficulty 
lies not so much in preventing the carriage from recoiling but 
in preventing the wheels from rising off the ground on the 
shock of discharge. The force of the recoil of the gun, acting 
in the line of motion of the center of gravity of the recoiling 
parts, tends to turn the carriage over backwards about the 
point of the trail or center of the spade. This force is resisted 



ELEMENTS OF GUN CONSTRUCTION AND DESIGN. 35 

by the weight of the gun and carriage, which tends to keep the 
wheels on the ground. The leverages with which the over- 
turning force acts is due to the distance of its line of action 
above the center of the spade; the leverage with which the 
overturning force acts is that due to the horizontal distance of 
the center of gravity of the gun and carriage from the center 
of the spade. 

It follows that the steadiness of the carriage for a given 
muzzle energy may be promoted by four factors. 

(a) Increasing the weight of the gun and recoiling parts. 
This reduces the recoil energy. 

(b) Increasing the length of recoil allowed. This re- 
duces the overturning pull. 

(c) Keeping this gun as low as possible either by re- 
ducing the height of the wheels, or by cranking the axle down- 
wards. This reduces the leverage of the overturning force. 

(d) Increasing the length of the trail. This increases 
the leverage of the steadying force. 

The well designed gun carriage is one that combines these 
factors in a practical way so as to give the greatest possible 
steadiness to the carriage at the same time keeping within 
the limits of weight imposed by the necessity of mobility. 

Gun carriages are constructed so as to permit movement 
of the tube in the vertical and generally in the horizontal 
plane. These two motions may be made simultaneous if so 
desired by proper combination of the two motions and the axis 
of a gun aligned in any desired direction within the limits of 
motion of its mount. The two motions referred to are de- 
signated as follows: (a) Rotation of the piece about a vertical 
axis, its inclination with the horizontal remaining unchanged 
is called "traverse." (b) Movement of the piece in a vertical 
plane the direction of the horizontal projection of the axis 
of the bore remaining unchanged is called ' 'elevation." 



36 FIELD ARTILLERY MATERIEL. 

In order to permit of the two motions mentioned, gun 
carriages are provided with mechanisms for giving the piece 
accurately controlled motion in both elevation and traverse. 
The elevating gear of most American guns is an application of 
the Chinese or Telescopic screw. This gives a short assembled 
length with the necessary extended length required for modern 
ranges. It also gives the necessary rapidity for action. An 
entirely different mechanism is used in our howitzers and 
American 75s. In this case motion is communicated to the 
rockers, which carry the gun and cradle, through the engage- 
ment of worms with teeth cut on the lower circular edge of 
the rockers, the latter being pivoted on the cradle trunnions. 

TRAVERSING MECHANISMS. 

Movement of the gun in traverse is accomplished in two 
general ways. 

(a) Pivot on the gun carriage axle. 

1. The gun and cradle move around a vertical pintle or 
pivot placed in a saddle or rocker which itself pivots on hori- 
zontal trunnions or bearings usually attached to the axle. 
The rear end of the rocker forms a seat or bearing on which the 
cradle and gun move in traverse. The upper end of the ele- 
vating screw is also attached to the rear end of the rocker. 
This allows the rocker and cradle to be moved together in 
elevation and the cradle to move on the rocker in traverse. 

2. The gun and cradle are mounted by means of horizon- 
tal cradle trunnions on a top carriage. The top carriage 
moves in traverse around a vertical pintle or bearing attached 
over the axle and between the front end of the trail flasks. 
The rear end of the top carriage moves on bearings attached 
to the top of each side of the trail flasks. This allows the gun, 
cradle and rocker to move in elevation with respect to the top 
carriage and the top carriage bearing the gun, cradle rocker 



ELEMENTS OF GUN CONSTRUCTION AND DESIGN. 37 

and elevating mechamism to move in traverse with respect 
to the bottom carriage. 

(b) The gun, cradle and trail move in traverse by sliding 
along the axle of the carriage on bearings provided for that 
purpose. In this case the trail spade is the point of pivot. 

The first system is the one generally used on all American 
gun carriages except the 155-mm Howitzer. It gives ease 
and speed in the manipulation of the piece in traverse, but has 
the disadvantage of rendering the carriage less stable in firing 
due to the fact that the direction of recoil of the gun is in the 
direction of the line joining the trail spade and the central pivot, 
only when the gun is absolutely in the centre of its traverse. 
In all other positions, which will be the usual case, there is a 
component at right angles to the line of trail spade-central 
pivot which tends to throw the gun off from its proper direc- 
tion making it necessary to relay each time the gun is fired. 
The second method is that in use on the French 75-mm gun 
and the French and American 155 howitzer. While not so 
easy of manipulation and giving less freedom of movement in 
traverse (about 106 mils) it still has the advantage in that 
it gives greater stability in firing due to the fact that the gun 
always recoils along the line through the trail spade, perpen- 
dicular to the axle. 

ELEVATING MECHANISMS. 

There are two general classifications of gun carriages 
according to the manner in which the laying for elevation is 
effected. The 3" gun is an example of one type in which the 
total quadrant angle of departure is laid off as one angle 
necessitating at each resetting of a range a new resetting of 
the range bubble. It is evident that this militates against 
both speed and accuracy in laying for elevation. The other 
type is illustrated by the American 75 and by the French and 
British 75-mm gun carriages which have what is called the 
''independent line of site." It differs from the other type in 



38 FIELD ARTILLERY MATERIEL. 

that there is placed between the top carriage and the cradle 
an intermediate carriage or rocker arm pivoting on the gun 
trunnions at one end, and carrying at the other the support 
for the elevating device which gives to the cradle and the 
gun the proper elevation for the range. This intermediate 
carriage or rocker arm has a toothed edge geared with a pinion 
fastened to the trail flask, by means of which, gun cradle and 
elevating device may be moved in elevation without disturbing 
the relation between itself and the gun, this being done by 
gears independent of the elevating mechanism. An angle 
of site may be set off for the intermediate carriage and after 
the bubble is centered this actuating pinion may be blocked 
and no further concern be paid to the angle of site. A can- 
noneer therefore has only to set his range accurately on the 
index to give the changes in range ordered. 

Elevation is accomplished by telescoping screws, by 
circular racks and. pinions, and by worms and arcs. Teles- 
coping screws are good for from 15 to 20 degrees in elevation 
only, as for greater angles they become rather too large and 
cumbersome. The elevating arc is attached on the top, on the 
bottom or on the side of the cradle and, if possible, at its 
centre. When the latter is not possible, two arcs are generally 
used to prevent torsional strains developing. Top racks are 
exposed to fire, side circular racks or arcs interfere with the 
traverse, with the placing of the sights, and with the general 
handling of the carriage. The bottom of the cradle is perhaps 
the best location for the rack. As in the traversing mechanism , 
a train of bevelled gears transmits the power from the hand 
wheel to the elevating mechanism. 

In both the traversing and elevating mechanism, strength, 
simplicity, power, accessibility, non-interference and absence 
of lost motion are the features sought. To secure these 
is one of the most difficult things in gun-carriage design; for, 
since the traversing and elevating are the last two elements 



ELEMENTS OF GUN CONSTRUCTION AND DESIGN. 39 

considered, they must, therefore, be the ground for modi- 
fication and the means of adapting the great main elements — 
namely, wheels, axle, trail, recoil mechanism and gun — 
into a unit. 

RECOIL MECHANISM. 

The recoil system of the gun carriage consists of a recoil 
brake, a counter recoil mechanism and a counter recoil brake. 
The function of each part is apparent from its name. Various 
systems of checking recoil on field guns have been used, 
among them may be mentioned; friction devices including 
brakes on the wheel, inclined planes, pneumatic and hydraulic 
brakes. All have either been superseded by the last named or 
are used in connection with hydraulic brakes. The power of 
the brake lies in the pressure produced in the cylinder through 
the resistance to motion offered by the liquid flowing through 
apertures. By varying the size of these apertures the braking 
effect may be controlled so as to fulfill the conditions demanded 
by the service. In designing the brake, the effect of the 
counter recoil system, angle of fire, length of recoil, friction 
and pressure within the cylinder must all be considered. In 
howitzers which are designed to be fired at high angles of 
elevation, the recoil must be shortened to prevent the breech 
striking the ground, a condition successfully met. Since 
the pressure due to recoil is ultimately led into the ground 
through the trail and spade, consideration must be given to 
the problem of the moment of inertia about the trailspade. 
The tendency to turn over backward about the spade as the 
center is offset by the amount of the weight of the carriage 
with respect to the same point. This raises the question as to 
how much pressure may be allowed to act to the rear; all of 
which must be considered in designing the carriage. The 
counter recoil systems in general use are two: spring or 
pneumatic. The former is illustrated in our 3" and 75-mm 



40 FIELD ARTILLERY MATERIEL. 

field guns, the latter by the French 75-mm gun and 155-mm 
howitzer. Their purpose, of course, is to return the gun "into 
battery" after it has recoiled on the carriage. 

The recoil mechanism is a study in itself, of which there 
are two schools — the advocates of the spring and of the air 
recuperators. Great Britain, Germany and the United States 
have been the advocates of spring recuperation and France 
of air recuperation. Great Britain and the United States 
were of the spring school, undoubtedly, because of the lack of 
a satisfactory air recuperating system; which is rather strik- 
ingly proven by the fact that both countries have adopted 
air recuperation since they have procured or developed satis- 
factory types. 

Both schools have grounds for their position, however. 
The spring school has in its favor simplicity of design and manu- 
facture and ease of replacement, which can be done in the 
field. On the other hand, spring recoils have many break- 
ages and greater weight combined with a high replacement of 
weakened springs, the life varying from 3000 to 8000 rounds. 

The air school has in its favor a high order of efficiency — 
smoother action, general all around efficiency and less weight. 
But the air recuperator is difficult to manufacture, costly, and 
when damaged must go to the rear to be repaired; which, 
however, it seldom needs. 

In mounting the spring recuperator, the most recent prac- 
tice has separated the recoil mechanism from the springs in 
order to distribute the piston rod pull, thus preventing whip 
and allowing easy access to the various parts for replacement, 
refilling and repairs. In order to lower the center of gravity, 
the gun is slung under the recoil cylinder with the two spring 
recuperators below and on either side. 

Air recuperators are invariably located below the gun for 
protection and because of their large size and shape, which 
adapt them for attaching the elevating mechanism. 




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42 FIELD ARTILLERY MATERIEL. 

In either system, the recoil is taken up by means of oil or 
glycerine and water passing through an orifice created by a 
slotted piston passing over ribs of varying height, or through 
a valve on the pressure side of the piston, or by a solid or per- 
forated piston passing through a perforated intermediate 
cylinder. 

The latter type is particularly adapted to variable recoil 
guns as the intermediate cylinder can be rotated, thus throw- 
ing varying orifices into position for the flow of oil. 

Counter recoil is accomplished by the springs or by the 
air pressure in the hydropneumatic system, in which the air 
pressure is sufficient to hold the gun in battery at all elevations 
and is built up at recoil. 

In all counter recoil systems, it is necessary to insert a 
buffer to take up the remaining energy of the springs or air 
pressure so as to bring the gun into battery without appreciable 
jar. Numerous types have been developed and perfected. 

The counter recoil brake or buffer in our 3 -gun is a 
slightly tapered bronze rod, tightly fitting in the cylindrical 
bore of the piston rod. The retardation caused by forcing 
the oil in the piston rod out through the small clearance 
between the buffer and bore of the piston rod eases the return 
to battery without jar to the gun, which has been forced 
back by the counter recoil springs. 

The physical law that action and reaction are equal has 
a peculiar emphasis when applied to the firing of a piece of 
high powered artillery. The force exerted to throw a heavy 
projectile 7 miles or more from the muzzle of the gun is toward 
the breech of the weapon in its recoil. How some of these 
forces are handled safely and easily by mechanical means 
are almost beyond the mind's grasp. Not long ago a tour- 
ing car, weighing two tons, traveled at the rate of 210 miles 
an hour along a Florida beach. Conceive of such a car going 
337 miles an hour — which is much faster than any man ever 



ELEMENTS OF GUN CONSTRUCTION AND DESIGN. 43 

traveled; then conceive of a mechanism which would stop 
this car, going nearly six miles a minute, stop it in 45 inches of 
space and one-half a second of time without the slightest 
damage to the car. This is precisely the equivalent of the 
feat performed by the recuperator of a heavy howitzer after 
a shot. 

SHIELDS. 

Although cover for the cannoneers had been used off and 
on since the invention of guns, it had fallen into disuse until 
it was firmly established as an essential feature by the French 
on their 75-mm in 1897. All modern field guns have such 
protection both for the cannoneers and for the delicate parts 
of the material which would be damaged by shrapnel balls or 
shell fragments. The shield is made of hardened steel capa- 
ble of withstanding the impact of a bullet of a service rifle 
at a 100 yds. range at a standard velocity. For convenience 
the shield is divided into three parts known as the top shield, 
main shield and apron, with suitable ports equipped with 
shutters for the line of vision from sights. The main is fast- 
ened to the axle and is rigid. The apron is hinged to the 
main shield or the axle-swinging forward for the traveling 
position. The top shield is fastened to the main shield by 
hinges and swings forward and downward for traveling posi- 
tion. 

SIGHTS. 

The sights serve three important functions. They im- 
prove the vision of the gunner and lay the gun in elevation 
and direction. The simplest sight is the one over the line of 
metal which lays for direction only, the second is the tangent 
sight mounted on a range arc centered on the axis of rotation 
in elevation usually having a deflection scale to correct for 
drift and to lead the moving target. This unit lays for range 
and direction. The last sight is the telescopic or panoramic 



44 FIELD ARTITLERY MATERIEL. 

sight which is mounted on a range arc and lays for direction 
only, it is the unit for indirect fire, laying for direction, and 
markedly improving the vision of the gunner. The latest 
model of the American panoramic sight is superior to any in 
existence. 

For precision in indirect fire, practically all carriages are 
equipped with some form of range quadrant, containing a 
means of setting off the angle of site and the range angle. All 
instruments are equipped to compensate for difference in 
wheel level. The British carriage automatically corrects for 
deviation, simplifying the firing date by that element. 

WHEELS. 

The height of the wheels affects the draft, weight, clear- 
ance, and stability of the carriage both as to road stability — 
i. e., low center of gravity; and firing stability — i. e., the over- 
turning movement about the end of the trail. It is now be- 
lieved that entirely too much stress has been laid on road 
clearance. Reducing the height of wheel reduces the weight 
and road clearance, lowers the center of gravity and increases 
the firing stability; but it also reduces the angle of gun eleva- 
tion unless the trail is shortened. Firing stability in general 
is increased by adding to the weight of the gun, lengthening 
the recoil, slinging the gun as low as possible and lengthening 
the trail. The less the height of the wheel exceeds four feet 
the better, despite the poor draft feature, which is compensated 
for to some extent by a reduction in weight and turning radius. 

AXLES. 

Axles are straight or of the offset type. The straight 
axle is stronger for its weight. The drop axle allows the center 
of gravity to be lowered. 



ELEMENTS OF GUN CONSTRUCTION AND DESIGN. 45 



TRAILS. 

Most modern trails are of the sectional built-up type. 
Some, however, are of tubular and telescopic. The most 
variable portion of the trail is the spade. It consists of two 
parts, the spade proper and the float. The former prevents 
recoil, the latter the burying of the trail. The spades proper 
are of three types: the fixed, as in the French 75-mm; semi- 
fixed, as in the 155-mm howitzer; and driven, as in the Deport 
and American 1916 75-mm. Each has advantages and dis- 
advantages. The driven spade is considered essential for the 
split trail carriage, as the latter has no means of seating itself; 
and should one spade take, and not the other the carriage 
might be damaged when the gun is fired at an extreme tra- 
verse. 

Split trails introduced a novelty in field gun carriages, 
in that a compensating device became necessary to adjust for 
the difference in ground level of the two spades. 

CONCLUSION. 

Guns are designed to function in a certain way. They 
are not temperamental. They follow absolutely and certainly 
fixed mechanical laws. If they fail there is a reason and it 
can be remedied. Certain parts are given certain shapes and 
forms, are machined to nice adjustments, and in taking down 
and assembling them, brains and dexterity are the tools to 
use rather than force and sledge-hammers. Learn from your 
text when and how to apply force and above all when not to 
use it. Treat these guns as you would a friend on whom you 
know you can depend. They will not fail you. 



46 FIELD ARTILLERY MATERIEL. 



CHAPTER IV 



MODERN ARMAMENT. 
THE ARTILLERY OF A FIELD ARMY; ITS FUNCTIONS. 

The artillery assigned to a field army should be of such 
mobility, power, variety and number as to insure the success 
of its purpose and to enable this success to be gained with the 
minimum of casualties. The latter point must receive careful 
consideration in studies of organization, for without adequate 
artillery preparation and support the successes of the most 
gallant infantry can in a series of actions become little more 
than phyrric victories. Many actions of our divisions in 
France resulted in casualties whose numbers decreased in pro- 
portion to the number of guns with which divisions were sup- 
ported. The proportion of guns to the thousand gross 
strength of infantry, cavalry, and machine guns adopted 
by the armies of the first class powers before the opening of 
the present European War in 1914 was: 

British, 6.8; French, 4.6; German, 6.4; American 3.2 
(Greble Board). 

During the war this proportion was constantly increased 
until at the close under conditions of position or entrenched 
warfare it was between 8 and 12 per thousand; this varied 
of course with the activity in different sectors. In quiet 
sectors and under conditions of maneuver, or open warfare, 
which necessitated leaving much artillery behind, it was about 
6 per thousand. 

A program of types of artillery weapons should be founded 
on the object and the means — that is, the destruction of the 
target and the projective to accomplish this. In the study of 
an artillery program there are two methods of approaching 



MODERN ARMAMENT. 47 

the subject. First, by starting with a minimum weight of 
projectile and working up to a reasonable maximum, according 
to some law and taking the corresponding calibers, a theoret- 
ical series of guns and howitzers can be expressed. For 
instance, if the law be doubling the weight of the projectile 
the series of types could be : 

Projectile of 13 pounds, caliber 3". 

Projectile of 26 pounds, caliber 4". 

Projectile of 52 pounds, caliber 5". 

Projectile of 104 pounds, caliber 6". 

Projectile of 208 pounds, caliber 8". 

Projectile of 416 pounds, caliber 10". 

Projectile of 832 pounds, caliber 12". 

Projectile of 1664 pounds, caliber 14". 

The second and more logical method, and one followed 
in our service, is to consider the artillery missions and deter- 
mine the types best suited irrespective of any theoretical 
series of weights and calibers. However, in the discussion of 
artillery missions and the proper types for their fulfillment 
there is a remarkable degree of unanimity of thought on these 
subjects; and the above table actually contains, with slight 
variations, the types that are most strongly recommended. 
While granting the great variety of artillery missions that 
often shade into each other, it is believed that they can best 
be considered in three great classes that follow the tactical 
composition of a field army: those of division, corps and army 
artillery. 

DIVISION ARTILLERY. 

Missions. The division artillery, first of all, must have 
the mobility that will permit it to accompany the infantry 
of a division and the maximum power consistent with that 
mobility; its object must be primarily the infantry of the op- 
posing division. It is therefore bound to its own infantry 



48 FIELD ARTILLERY MATERIEL. 

with the closest bonds and its tactical use cannot be separated 
from that of the infantry. The division artillery must fire, 
accurately, a man killing projectile and be prepared for quick 
changes of targets ; it must have a great range because of depth, 
both of its own and the enemy division; it must continually 
harass the enemy, prevent his movement and force him into 
cover or protected trenches. On the defensive it must break 
up the opposing infantry formations by preparing a counter- 
offensive fire and by annihilating fire on points from which the 
enemy attacks emerge; and, failing in these, be prepared to use 
the barrage and shrapnel fire at close range. In the offensive 
the division artillery must play its part in the complex schemes 
of artillery preparation by cutting wire, destroying machine 
gun nests, gassing areas, concentrating on infantry positions 
and taking the principal part in the deep barrage that should 
precede the infantry attack. Its fire, accompanying the 
infantry movement, requires its own movement and by its 
mobility it often becomes for some time the sole artillery pro- 
tection in the preparation and holding of a position which 
has been taken. 

Light Gun and Howitzer. The consensus of opinion of 
artillery officers is that the division artillery missions are 
best fulfilled by a light field gun and a light field howitzer 
having a range of at least 11,000 yards. While differing in 
mechanical features, the field guns of the different European 
countries are practically of the same type and, though con- 
stant effort is being made to improve details, they can be 
stated as generally satisfactory to their own governments 
and not liable to any radical changes. The general type of 
field gun, while capable of fulfilling most of the division artillery 
missions, must be supplemented by a proper howitzer. There 
are many instances where the terrain or the lay of the land 
offers such protection to the infantry that the field gun can- 
not bring an effective fire. The howitzer has the great ad- 



MODERN ARMAMENT. 49 

vantage that with the proper set of propelling charges and, 
therefore, choice of trajectories for the same range, protected 
positions can be chosen for howitzers that guns could not 
use, and angles of fall obtained on objectives that the normal 
ammunition of guns would not give. The low muzzle velocity 
of howitzers admits of their almost continuous use in harassing 
fire and allows the use of a projectile double the weight of that 
of a field gun. Such a howitzer renders excellent service in 
wire cutting and is a useful projector of gas shells. To insure 
the mobility required of all divisional artillery the weight of 
the howitzer and carriage should not exceed that of the field 
gun, or about 4,500 pounds. 

Light Gun Discussion. The consensus of opinion of all 
artillery officers — French, English and American — is that the 
75-mm gun, or approximately this caliber, firing a 15-pound 
projectile or a projectile of approximately this weight, and 
having a range of not less than 11,000 yards, is a satisfactory 
weapon at the present time for use with the division artillery. 
The projectile in question, whether a shrapnel or a high ex- 
plosive shell, satisfies adequately the criterion of man-killing. 
At the close of the war the nations were not entirely in accord 
with respect to their conception of an up-to-date carriage for 
a light field gun. All the nations whose tendencies have been 
considered in this report have experienced to a varying degree 
with field gun carriages, particularly in a desire to design a 
carriage permitting a greater angle of elevation and greater 
movement of the gun in the traverse. The Italians have ex- 
pressed themselves in the modified Deport Carriage; this 
vehicle is of the split trail type and permits an elevation in 
excess of 75 degrees, and a traverse on each side of the center 
of the carriage of about 20 degrees — about 356 mils. Up to 
the time that the board left France it was not possible to learn 
the French decision in the matter of a split trail carriage for 
their light field gun. It is known, however, that several types 

T. B.— 4 



50 FIELD ARTILLERY MATERIEL. 

of this carriage have been designed and tested; it is known, 
also, that considerable favor has been found with the American 
1916, which type has been tested under the auspices of the 
French Government. In England, however, the board was 
not able to develop any enthusiasm for the split trail type, 
although the matter had been seriously considered. In that 
country the up-to-date field gun carriage appears to be ade- 
quately expressed in their new 18-pounder. The vehicle 
upon which this gun is mounted permits an elevation of 37 
degrees and an axle traverse of 4 3^2 degrees on each side. The 
trail is a box trail and the carriage is simple and steady in its 
construction and lends itself to rapid production. 

Motorization. At some time in the future it is probable 
that all the division artillery will be motorized. The result 
of such a change in the prime mover would be to remove the 
present restriction as to weight of gun and carriage. The 
board senses a demand in the near future for a light field gun 
having a maximum range of approximately 15,000 yards; 
such a range may be achieved by increasing the muzzle velocity 
and, perhaps, the weight of the projectile, although change in 
the form of projectiles will give some improvement over the 
present ranges. It is probable that the limiting features in 
the design of field guns of the future will be the requirement 
that it should pass safely over temporary pontoon bridges and 
that the weight and form and size of ammunition must be 
such that the present rate of fire will not be slowed down. 
The board is of the opinion that, except as to perfection of 
details, the limit of carriage design, as expressed by the 
most modern type of box-trail and split-trail carriages, has 
been reached; and feels that with the advent of motor trans- 
portation the tendency will be toward a gun mounted on a 
self propelling carriage and expressing the desires of the field 
artillery with respect to maximum horizontal and vertical 
arcs of fire. 



MODERN ARMAMENT. 51 

Light Gun. Ideal. A gun of about 3" caliber on a car- 
riage permitting a vertical arc of fire of from 5 degrees depres- 
sion to 80 degrees elevation and a horizontal arc of fire of 360 
degrees; a projectile weighing not over 20 pounds, shrapnel 
and high explosive shell of satisfactory man-killing character- 
istics with maximum range of 15,000 yards; fixed ammunition, 
smokeless, flashless propelling charge; time fuse for shrapnel. 
With shell having safe fuses with different lengths of delayed 
action after they land. The high explosive shell should be 
of one type only. Two propelling charges should be furnished, 
a normal charge for about 11,000 yards range and a super 
charge for maximum range. The proportion should be 90% 
of the former and 10% of the latter. A maximum rate of 
fire of 20 rounds per minute is deemed sufficient. 

Light Gun. Practical. For the present, arm brigades 
with 75-mm materiel. Models 1916, 50%, and 1897 
(French), 50%. 

Transport. Ideal. Mechanical transport is the prime 
mover of the future. The introduction of mechanical trans- 
port will undoubtedly cause far-reaching changes in the types 
of gun carriages. It is not possible now to state just how far 
this will go or whether a gun mounted on a self propelled 
vehicle or one mounted on some type of trailing vehicle will 
be the final result. Both types may be necessary. It is 
urgent that study and development be carried along these 
lines, as we are on the verge of changes fully as radical as the 
introduction of the long recoil field gun and carriage, and the 
country first utilizing the new capabilities opened up by mech- 
anical traction and the caterpillar will have a great advantage 
in the next war. A limit of 4,500 pounds behind the team has 
heretofore been imposed on the artillery of this class. The 
corresponding limit in the future will probably be that im- 
posed by pontoon bridges. 



52 FIELD ARTILLERY MATERIEL. 

Transport. Practical. Therefore it is thought that four 
regiments of 75- mm guns (two regiments of French Model 
1897, and two regiments of U. S. Model 1916) should be im- 
mediately equipped with motors, the remainder to be horsed; 
mechanical transport to gradually replace horse only after 
the tractor demonstrates its superiority in service. 

Light Howitzer Discussion. The consensus of opinion 
of American army officers consulted is that a howitzer about 
4 in caliber, firing a projectile weighing from 25 to 30 pounds 
at a maximum range greater than 10,000 yards, is required. 
This opinion is concurred in by the French, Italians and 
English, and it appears to be definitely established that the 
mobility of the light field howitzer should be practically the 
same as that of the light field gun. The British army was 
equipped with a 4J/£ // howitzer, firing a projectile weighing 
35 pounds and with a maximum range of 7,700 yards; the 
weight of the howitzer limbered is 4676 pounds — 150 pounds 
more than the weight of the 18-pounder field gun. No ev- 
idence was found that the British Government intended mak- 
ing any alterations in the design of this howitzer; naturally 
they will attempt to increase the range, power and accuracy 
of the projectile by change in its weight, its capacity and its 
form. The French artillery was not equipped with the light 
field howitzer of approximately the same weight as the 75-mm 
field gun. During the war it was found impracticable to 
construct a lighter howitzer without interfering with the 
production of other calibers which were considered more 
important. In the earlier stages of the war the Italian artillery 
was not equipped with a light field howitzer; however, before 
the end of 1917 orders were placed for several hundred how- 
itzers of the 105-mm type. It should be noted that several 
hundred howitzers of this caliber were being constructed 
before the armistice and that many have been captured from 
the Austrians by the Italians; this, so far as the Italians were 



MODERN ARMAMENT. 53 

concerned, makes it certain that a light field howitzer will be 
furnished by the Italian army. The German and Austrian 
armies were equipped with a howitzer of the light field type; 
this weapon had a caliber of 105-mm type. 

It fired a projectile weighing 34.54 pounds at a maximum 
range of 10,500 yards. (Streamline shell.) The weight of 
the howitzer limbered was 4,500 pounds. In the opinion of the 
board, the Germans have proceeded on sound principles in 
their development of the light field howitzer. Their '98 model 
was a companion piece to their '96 field gun and in the years 
that passed from 1898 to 1916, which included their early war 
experience, they kept to the idea of the relation of the two 
pieces even to the extent of including in a field artillery regi- 
ment one battalion of light howitzers. Their 1916 models 
of both light gun and howitzers show the endeavor to keep 
the pieces in the same class; that is, the weight of the gun and 
howitzer in action nearly the same, 2,750 pounds and 2,700 
pounds; the weight of the gun limbered and the howitzer 
limbered are the same, 4,500 pounds; the elevation of both 
the same — minus 10 to plus 40 degrees; the carriages are of 
the same type; and the extreme ranges of gun and howitzer are 
respectively 11,700 and 10,500 yards. From the foregoing 
it is seen that all the important belligerents except the French 
and the Americans were equipped with a light field howitzer 
firing a projectile about twice the weight of the light field 
gun projectile and having otherwise the same general charac- 
teristics. There is no evidence to show that the fire of the 
French and the American artillery was not fully effective as 
that of any other artillery; however the testimony of the 
French and American artillery officers is to the effect: 

(a) That the lightest howitzer in use, i. e., the 155-mm, 
was not sufficiently mobile to be a suitable companion piece 
for the 75- mm gun. 



54 FIELD ARTILLERY MATERIEL. 

(b) That many times the fire of the 75-mm gun proved 
ineffective due to its fiat trajectory; a howitzer would have 
been more effective in the attack of certain targets. 

(c) That a large volume of fire is necessary. 

(d) That while the 155-mm howitzer is more power- 
ful than the light field howitzer its consumption of ammunition 
for many purposes is wasteful and extravagant and its volume 
of fire is insufficient. 

(e) That the light howitzer is particularly suited for the 
destruction of wire entanglements; its better accuracy and 
more powerful projectile make it more suitable than the field 
gun for that purpose. 

(f) That the 75-mm field gun projectile is not so satis- 
factory a gas shell as the howitzer projectile which has greater 
weight. 

Light Howitzer. Idea. A weapon of about 105-mm 
caliber on a carriage permitting a vertical arc of fire from minus 
5 degrees to plus 65 degrees, and a horizontal arc of fire of 360 
degrees. Efforts should be made to develop a carriage 
which can be used interchangeably for the division light gun 
referred to above and this howitzer. The projectile should 
weigh about 30 to 35 pounds and should include both shell 
and shrapnel. A maximum range of 12,000 yards will be 
satisfactory. Semi-fixed ammunition with varying charges 
should be used, otherwise the ammunition should be similar 
to that provided for the 75-mm guns. 

Light Howitzer. Practical. For the present, the division 
should be armed with the 155 howitzer, Schnieder, but active 
development and test should be made on a type as stated under 
"Ideal" above, and with the ammunition and other accessories 
to it. Upon the development of the carriage as nearly ap- 
proximating the ideal as may be practically possible, efforts 
should be made to secure quantity production in order that it 



MODERN ARMAMENT. 55 

may be incorporated in the division as recommended. In 
addition, a split trail carriage for this howitzer should be 
developed. 

Transport. The light howitzer should have the same 
means of transport as the light field gun and the same re- 
marks heretofore made as to the probable future development 
of the field gun also apply to the howitzer carriage. 

CORPS ARTILLERY. 

Missions. It will be noted above that the division ar- 
tillery missions did not include their own protection against 
the enemy artillery. This counter-battery work is the princi- 
pal mission of the corps artillery. The corps artillery has 
also the mission of extensive harassing and interdicting fire 
along the corps front and to a greater depth than the capa- 
bilities of the division artillery; also of destructive fire on 
strong points as well as on railroad facilities and points of 
supply. For the accomplishment of these corps artillery 
missions there are two types of artillery necessary, a gun and 
a howitzer, each having 16,000 yards range and each weighing 
with the carriage about 11,000 pounds. There is another 
class of artillery called anti-aircraft artillery to be considered. 
This is used first in providing anti-aircraft defense for army 
zones, for certain areas in rear of armies or along a certain 
line of anti-aircraft defense. 

Medium Gun Discussion. The consensus of opinion of 
artillery officers — Italian, English and American — is that a 
medium gun of about 6" caliber is necessary. The medium 
type gun furnished to the American army was the 4.7 (Model 
1906). This gun has a maximum elevation of 15 degrees 
with a corresponding maximum range of 8,750 yards. The 
British army was equipped with the 5" gun — the carriage 
permits a maximum elevation of 21 degrees and 30 minutes, 



56 FIELD ARTILLERY MATERIEL. 

giving a maximum range of 12,500 yards. The French army 
was equipped with, to a certain extent, the 105-mm and the 
140-mm gun. The 105-mm gun a maximum elevation of 
37 degrees, with a maximum range of 13,900 yards. The 
140-mm gun has a maximum elevation of 30 degrees and, with 
a high velocity, has a maximum range of 19,500 yards. The 
French 105-mm gun is a modern weapon (1913). The Ger- 
man artillery was equipped with a 105-mm gun (M-1917) with 
a maximum elevation of 45 degrees, and a maximum range 
of 16,000 yards. The German army was also equipped with 
the 130-mm gun, having a maximum range of 16,500 yards. 
The Austrian army was similarity equipped. The Italians 
were equipped with a 105-mm gun essentially of the same char- 
acteristics as the French 105-mm M-1913. 

Medium Gun. Ideal. A caliber of between 4.7 and 
5" on a carriage permitting a vertical arc of fire of from minus 
5 degrees to plus 80 degrees; a horizontal arc of fire of 360 
degrees. Shrapnel and shell weighing not over 60 pounds, 
maximum range 18,000 yards; with semi-fixed or separate 
loading ammunition permissible. 

Medium Gun Practical. Corps artillery should be armed 
with the present type 4.7" gun, Model 1906, except that at 
least one regiment should be armed with the British type 
5 "-guns purchased abroad. 

Transport. All corps guns should be developed for long, 
rapid hauls. Similar ammunition vehicles should be de- 
veloped. The wheels for the gun carriage should be rubber- 
tired. 

Medium Howitzer. In the opinion of the French, Italians, 
British and the Americans, the 155-mm howitzer (Schnieder) 
was conspicuously successful in the present war. It should, 
therefore, be retained as a type. The howitzer and carriage 
as it stands at present, is a highly satisfactory and efficient 



MODERN ARMAMENT. 57 

piece of armament. For the future it is believed that effort 
should be made to increase the range by improvements in the 
form of projectile, and it is believed that the form of how- 
itzer and carriage should be studied with a view of obtaining, 
through modifications, a maximum range of approximately 
16,000 yards. 

Many batteries of 155-mm howitzers (Schnieder) were 
motorized in the American Army in France, and the con- 
census of opinion is definitely toward the retention of this 
form of prime mover. It is interesting to note that all the 
important belligerents have settled upon a howitzer of ap- 
proximately 6" in caliber, and otherwise essentially of the 
same ballistic characteristics as the type in question. The 
projectile of this caliber is the smallest projectile which can be 
called upon to give adequate mining effect against material 
targets of semi-permanent nature. The place of this how- 
itzer is, therefore, determined by considerations of its destruc- 
tive ability. It is a splendid destruction and neutralizing 
weapon. 

Medium Howitzer. Ideal. A caliber of about 155-mm 
on a carriage permitting a vertical arc of fire of from minus 
5 degrees to plus 65 degrees; and a horizontal arc of fire of 360- 
degrees. The projectile should not weigh over 100 pounds 
and should be interchangeable with projectiles for other guns 
of this caliber referred to later on. High explosive shell, 
only, should be supplied. 

Medium Howitzer. Practical. The corps should be 
armed with the 155-mm (Schnieder) howitzer referred to 
above. The type of fuses for shell should be super quick and 
long delay. 

ARMY ARTILLERY. 

Missions. In addition to the division and corps artillery 
fulfilling the missions outlined above there must be additional 



58 FIELD ARTILLERY MATERIEL. 

artillery available. There are missions of interdiction, neu- 
tralization and destruction which fall beyond the activities or 
capabilities of the normal corps or medium field types; there 
must exist a surplus of division or corps types, properly trans- 
ported, for strategic reinforcements of divisions and corps 
during such times as the normal allottment to such units is 
insufficient ; there must be artillery of special purpose — moun- 
tain artillery, trench and super guns and howitzers. Of the 
above additional artillery, a type of heavy field gun and a type 
of heavy field howitzer are considered normally necessary in 
the armament of a field army; the gun should have a range 
of approximately 25,000 yards, and the howitzer a range of 
about 18,000 yards. These weapons are more powerful than 
the medium field types, add range to the interdiction and 
harassing and to the neutralization and destruction possible 
with the corps type. Considering the paragraphs pertaining 
to divisional artillery and the introduction to corps artillery 
it will be seen that the normal artillery of a field army can be 
accomplished by the assignments of two caliber, i. e., two light 
weapons, two medium weapons and two heavy weapons — a 
gun and a howitzer in each class — and a satisfactory anti- 
aircraft gun. 

Heavy Field Gun. The consensus of opinion of all artil- 
lery officers — British, Italian and American — is that the heavy 
field gun should be of approximately 6" caliber and that guns 
of greater caliber than this are necessary in limited number for 
field operations. The French were constructing 194-mm 
guns during the latter stages of the war. It is believed that 
in developing this type of gun the French were actuated 
almost entirely by the necessity for increased range, since the 
German 150-mm gun, Model 1916, outranged the G. P. F. by 
approximately 5,500 yards. The French have recently made 
considerable progress in securing the necessary increase in 
range with the G. P. F. All of the principal nations engaged 



MODERN ARMAMENT. 59 

in the war used a heavy field gun of approximately 6" caliber. 
This type has given such general satisfaction that its contin- 
uance is assured. The principal mission of the heavy field 
gun is harassing and interdiction fire, and for these uses the 
6" projectile is sufficiently heavy. The maximum practicable 
traverse and elevation should be provided by the carriage of 
the heavy field gun. The G. P. F. carriage has given general 
satisfaction, but its wide tread and the excessive time required 
to occupy a position are very objectionable features. It is 
the consensus of all artillery officers — French, British and 
American — that the heavy field gun should be of approxi- 
mately 6" caliber and with a range in excess of 25,000 yards, 
with not less than 60 degree traverse, weighing not more than 
12 tons, limbered, capable of occupying and leaving a position 
quickly, and with a width of tread which does not prevent 
two-way traffic on ordinary roads. The Italians differ from 
this opinion only in that they are satisfied with a maximum 
range of 18,000 yards. 

Heavy Field Gun. Ideal. A caliber of about 155-mm 
on a carriage permitting a vertical arc of fire from degrees to 
plus 65 degrees; with a horizontal arc of fire of 360 degrees. 
The maximum range should be about 25,000 yards. 

Heavy Field Gun. Practical. Arm with the present 
type 155-mm G. P. F. and carry on experiments for type of 
carriage as outlined for division field gun. The fuses should 
be super-quick and short delay. 

Transport. All artillery of this type should be motorized 
and tested and experiments for ammunition vehicles to cor- 
respond with the types of carriages developed, and should be 
carried on simultaneously. 

Heavy Field Howitzer. No type of heavy field howitzer 
developed during the war has given general satisfaction. The 
consensus of all army artillery officers — French, English and 



60 FIELD ARTILLERY MATERIEL. 

American — is that two calibers of howitzers are necessary — 
one a companion piece for the 6" gun and one of the maximum 
possible power consistent with the necessary mobility. The 
lighter of these two howitzers should have the same mobility 
as the 6" gun, with a caliber of about 8" and a maximum 
range of not less than 16,000 yards. The heavy field howitzer 
should be of about 9,5" caliber with a range in excess of 16,000 
yards ; the carriage should provide for wide traverse and must 
have sufficient mobility to accompany the army in the field. 
It will probably be necessary to transport this howitzer in 
more than one load, and the maximum weight of any load 
should not exceed 12 tons. The average time necessary for 
occupying a position should not exceed six hours under actual 
field conditions. 

Heavy Field Howitzer. Ideal. A caliber of about 8" 
on a carriage permitting a vertical arc of fire of from to 
plus 65 degrees; and a horizontal arc of fire of 360 degrees. 
The maximum range should be 18,000 yards. 

Heavy Field Howitzer. Practical. Use at present 8" 
material of British design which is on hand. 

Railway Artillery. The war has demonstrated the neces- 
sity for long range and powerful guns for distant interdiction 
and harassing work and for super-heavy howitzers for the 
destruction of semi-permanent fortifications. Artillery of 
these types can best be mounted on railway carriages and this 
type of mount offers no serious disadvantages since these guns 
will not be used except with large forces which require ex- 
tensive railroad systems for their supply. This does not 
apply to guns of the type used to bombard Paris; such guns 
have no military value and their construction is not justifiable. 

ANTI-AIRCRAFT GUNS. 
Light Gun. Ideal. Caliber about 3" with initial velocity 
of at least 2,600 f. s.; semi-automatic breechblock, mounted 



MODERN ARMAMENT. 61 

on carriage, permitting 80 degrees elevation and 360 degrees 
traverse; projectiles weighing not less than 15 pounds, of one 
type high explosive shell with maximum ballistic qualities 
and as large explosive charge as possible; fixed ammunition; 
smokeless, flashless powder, mechanical fuse. In this type 
every effort must be made to increase the rate of fire and de- 
crease time of flight; this latter is limited only by considera- 
tions of a reasonable accuracy life for the gun. 

Light Gun. Practical. Arm units with present 3" anti- 
aircraft equipment. Continue experiments leading to the 
development of the ideal. 

Transport. Ideal. Caterpillar mount or caterpillar 
trailer mount drawn by caterpillar tractor, each unit to per- 
mit a sustained speed of 12 miles per hour. 



62 FIELD ARTILLERY MATERIEL. 

CHAPTER V 
THE 3-INCH FIELD GUN. 

THE GUN. 

The Gun is known officially as the 3-inch Field Gun, 
Model 1905. It is a built-up construction of nickel-steel and 
consists of a tube with a rifled bore, 3 inches in diameter, upon 
which are shrunk the jacket, locking hoop and front clip hoop. 
The jacket reinforces the rear half of the tube. The locking 
hoop serves to secure the jacket from any longitudinal move- 
ment to the rear. On the under side of the gun, extending 
the entire length of the jacket, locking hoop, and front clip, 
are formed two recoil guides or clips which fit over and secure 
the gun to the guide rails of the cradle. When the gun is 
fired, it slides along the guide rails. The dust guard covers 
the part of the guide rails between the locking hoop and the 
front clip. The rifling of the bore is right-hand twist and starts 
with turns at the breech increasing to 1 turn in 25 calibers 
at 10 inches from the muzzle, then uniform to the muzzle. 

Weights and Dimensions. 

Weight of gun 788 lbs. 

Calibre 3 inches 

Length about 7 feet 

Number of lands and grooves 24 

Muzzle velocity 1700 ft. sec. 

Maximum pressure per sq. in 33,000 lbs. 

Limit of depression (90 mils.) 5 degrees 

Maximum elevation (265 mils.) 15 degrees 

Maximum range, trail sunk, about 8,500 yds. (5 M) 

Range at 15° elevation (265 mils) 6,000 yds. (3J^ M) 



THE 3-INCH FIELD GUN. 63 

Nomenclature of parts o f Gun : — 

Jacket. Front clip. 

Locking hoop. Muzzle. 

Tube. Dust guard. 

Bore. Recoil guides or clips. 

Rifling. Chamber. 

Lands. Recoil lug. 

Grooves Line sight (front and rear). 

Breezh recess. Handy oilers. 

THE BREECH MECHANISM. 

The breechblock is of the interrupted-screw type, and is 
provided with four threaded and four slotted sectors. The 
front end of the axial recess in the block is closed by a bushing. 
Four ventholes lead from a cavity in the bushing and permit 
the escape of gas to the rear in case of a ruptured primer. On 
the rear face of the breechblock are cut gear teeth, in which 
the gear teeth of the operating lever bevelgear mesh. The 
breechblock is concentrically mounted on a hub on the block 
carrier, in which the firing-lock case is fitted. Its position in 
the breech of the gun with reference to the axis of the bore is 
eccentric. 

The breechblock is closed or locked by a continuous move- 
ment of the operating lever. When the block is swung to the 
closed position the front face of the block latch comes in con- 
tact with the rear face of the breech of the gun, thus forcing 
the latch out of the notch in the breechblock and back into a 
recess in the carrier. By continuing the motion of closing the 
mechanism, the breechblock is then rotated on the hub of the 
carrier and its threads engage with corresponding ones in the 
gun. When the breechblock is in the closed position, a lug 
on the firing-lock case serves to lock the carrier to the breech- 
block and prevents displacement due to a blowback. 



64 FIELD ARTILLERY MATERIEL. 

The firing mechanism belongs to that type known as a 
continuous-pull mechanism; that is, no cocking of the firing- 
pin is required. 

The firing-lock case is eccentrically fitted in the hub of the 
block carrier, in such a position that the axis of the firing-pin 
is always in line with the bore of the gun. The vent bushing 
in the front end of the breech block through which the firing 
pin passes when in the fired position, is fitted eccentrically with 
reference to the breechblock. This eccentric arrangement of 
the breechblock, masks the point of the firing-pin and prevents 
any possible contact between the pin and the primer in the 
cartridge case when the block is unlocked. The block will be 
practically fully locked before any contact between the 
firing-pin and primer can take place. 

Nomenclature of important parts of Breech & Firing 
Mechanism. 

Mod. 1905:— 

Name of Part Where located 

Breech Block On block carrier 

Vent Bushing Front end of block 

Block Carrier Hinged to jacket; supports block 

Block Stop Screwed into front face of carrier 

Hinge Pin Hinges carrier to jacket 

Hinge Pin Catch In hinge pin 

Extractor In breech recess 

Extractor Lever Mounted on hinge pin 

Operating Lever Pivoted on block carrier 

Lever Pivot Pivots lever on block carrier 

Lever Latch In operating lever 

Lever Latch Spring In operating lever, lower part 

Lever Latch Pivot In operating lever, lower part 

Block Latch In recess in carrier 

Block Latch Spring Around latch bolt 

Firing Lock Case In hub of the block carrier 

Locking Bolt Nut and Pin On firing lock case, rear face of carrier 

Firing Pin In axle hole, center of firing lock case 



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THE 3-INCH FIELD GUN. 65 

Name of Part Where Located 

Firing Pin Spring Around firing pin 

Firing Spring Sleeve Around firing pin spring 

Sear ; ... In slot in firing lock case 

Trigger Fork Rear end firing lock case 

Trigger Shaft On rear end firing lock case 

Trigger Shaft Detent On trigger shaft 

Firing Pallet On pallet shank 

Pallet Shank On recoil lug of gun 

Firing Handle On firing handle shaft 

Firing Handle Bracket Attached to right side of cradle 

Firing Handle Shaft Assembled in bracket, right side of cradle 

Trip Latch Attached to trip latch plunger 

Trip Latch Plunger .Assembled to firing handle 

Adjusting Screw Assembled to firing handle bracket 

Check Nut Assembled in adjusting screw 

THE GUN CARRIAGE. 

The gun carriage for the 3-inch gun Model 1905 is of the 
type known as the long- recoil, in which the gun is permitted 
a sufficient length of recoil (about 45 inches) upon the carnage 
to render the latter stationary under firing stresses. The gun 
is mounted upon a cradle which forms a housing for the recoil 
controlling parts. The cradle rests upon the rocker and has 
a small traversing motion of 70 mils on each side of the axis 
of the carriage. The rocker is jdurnaled upon the axle and its 
rear end is supported by the elevating mechanism, which is 
seated in the trail. 

The principal parts of the carriage are the wheels, axle, 
trail and elevating mechanism forming the lower carriage, the 
cradle and recoil-controlling parts constituting the upper 
carriage, and the rocker and traversing mechanism intermedi- 
ate between the two. In addition there are provided shields, 
ammunition carriers, the road brake, and the axle seats. 

The Wheels and the Axle. The wheels are a modified 
form of the Archibald pattern, 56 inches in diameter, with 

T. B— 5 



66 FIELD ARTILLERY MATERIEL. 

3-inch tires. The axle is hollow and forged from a single piece 
of steel. The wheels are held on by the wheel fastenings. 

Trail. — The trail consists of two steel flasks of channel 
section with the flanges turned inward, tied together by tran- 
soms and plates to form the sight and the tool boxes. At- 
tached to the trail are the trail spade, float trail hand-spike, 
trail handles and the lunette. 

Elevating Gear. — The elevating gear is of double- screw 
type and consists of an inner and outer elevating screw, 
an elevating-gear bracket, an elevating bevel gear, two eleva- 
ting bevel pinions, and two elevating crank shafts. The inner 
elevating screw is a steel screw, threaded with a right-hand 
thread. It is attached at its upper end by the elevating pin 
to the rear end of the rocker. The outer elevating screw is of 
bronze and is threaded on the exterior with a right-hand 
thread to take the inner elevating screw. On the exterior are 
also cut two longitudinal keyways, in which the keys of the 
bevel gear work. 

Traversing Mechanism. — The traversing mechanism 
consists of a shaft, called the traversing shaft, mounted 
in bearings in the traversing-gear case, and a traversing nut 
moving longitudinally on the shaft, but restrained from turn- 
ing with it by its bearings in the gear case. A cylindrical lug 
on top of the nut fits in a hole in a bronze traversing link, the 
right end of which is pivoted by the traversing-link pivot to 
the traversing lug on the underside of the cradle. This pivot 
is secured to the cradle- traversing lug by a nut and split pin. 
The left bearing of the traversing shaft is split for the purpose 
of assembling and rests between two collars on the shaft. The 
bearing, with the shaft in place, is slipped into its seat in the 
gear case, where it is held in position by two pins. 

The Cradle Complete. — The cradle supports the gun, 
guides it in recoil, and forms a housing for the recoil-controlling 



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parts; it consists of a flange steel body with the upper edges 
flanged outward. The flanges are bronze lined, engage the 
clips on the gun, forming the guide rails for the gun on recoil. 
Riveted to the bottom of the cradle are four steel forgings, the 
pintle, traversing lug, rear clip, and elevating and traversing 
lock lug. The pintle fits the pintle socket in the rocker and 
forms a bearing upon which the cradle is traversed. The 
traversing lug has been heretofore mentioned as affording a 
point of attachment for the traversing-link pivot. The cradle 
rear clip, in addition to embracing the rear end of the rocker, 
has a broad bearing on the latter directly over the point of 
attachment of the elevating screw. 

To relieve the pointing mechanism from all strains in 
travelling, an elevating and traversing lock is provided, by 
which the cradle may be securely locked to the trail. 

The recoil-controlling parts contained inside the cradle 
are the cylinder, the piston rod, the counter-recoil buffer, the 
counter-recoil springs and the spring support. 

To the rear end of the cradle is riveted a steel cradle 
head, rear, through which the cylinder moves in recoil and 
projects for attachment to the recoil lug on the gun by means 
of the cylinder end stud and nut. The front end of the cradle 
is closed by the cradle head, front, and the retaining ring. 

The cylinder lies inside the cradle and is surrounded by 
the counter-recoil springs. Its rear end is closed and has a 
projection on the inside to which is screwed the counter-recoil 
buffer, a tapered bronze rod which fits with small clearance 
into a bore at the rear end of the piston-rod. The front end 
of the cylinder is closed by a bronze oiltight gland, through 
which the piston-rod slides. The cylinder is filled with a 
neutral oil called hydroline. The interior of the cylinder is 
cylindrical. Three longitudinal ribs or throttling bars of uni- 
form width but varying height extend along the interior from 
the rear end to within 19 inches from the front end. Three 



THE 3-INCH FIELD GUN. 69 

notches are cut in the piston head, forming ports for the 
passage of the liquid from one side of the piston to the 
other. The height of the throttling bars is calculated so 
that the resistance which the liquid offers, plus the resistance 
of the springs, is constant and such that the recoil will be 
checked at the desired point. During recoil the front end 
of the cylinder is supported by the spring support. 

The piston rod is of steel, and is provided with a bronze 
piston head, screwed against a shoulder at the rear end. 
The head has three notches cut in its perimeter, which fit over 
the throttling-bar projections on the cylinder wall. The 
rear end of the piston is bored out to take the counter-recoil 
buffer. In counter recoil the oil in this bore can escape cnly 
by a small clearance. In this way the return of the gun into 
battery is so eased and regulated that very little shock and 
consequent derangement of the aim of the piece occur. The 
front end of the piston-rod is attached to the cradle head, 
front, by means of the piston-rod nut. 

The counter-recoil springs (three in number each 36 
inches long) are helical, being made from a rectangular steel 
bar coiled on edge. They are assembled in the cradle, end 
to end around the cylinder and bear in front against the spring 
support and in the rear against the cradle head, rear. They 
are assembled under an initial compression of approximately 
750 lbs. which is sufficient to return the gun into battery at 
the maximum elevation. In place of the single counter- recoil 
springs a set of three inner and three outer counter-recoil 
springs is also being issued. 

The spring support forms a support for the front end of 
the cylinder and a bearing for the front end of the spring 
column. It has guide lugs which fit into and glide along guide 
rails inside the cradle during recoil. The spring support is 
held in place by the retaining ring. 



70 FIELD ARTILLERY MATERIEL. 



Action of the Mechanism. 

The action of the recoil mechanism when the gun is fired 
is as follows: — The gun moves to the rear 45 inches on the 
cradle, carrying with it the cylinder and compressing the recoil 
springs. The piston rod being attached to a fixed part of the 
carriage in front, (the cradle-head) does not move. Therefore, 
since the cylinder moves to the rear, the oil in it must pass 
from one side of the piston head to the other. The energy of 
recoil of the gun is therefore absorbed by the resistance which 
the oil offers when being forced through small openings between 
the notches in the piston head and the throttling bars along 
the inside of the cylinder and also by the resistance of the 
counter-recoil springs to additional compression. The energy 
stored up by the springs during this compression, returns 
the gun and cylinder to the firing or original position. This 
return movement is eased and regulated by the counter-recoil 
buffer. The piston rod pull and the spring resistance are trans- 
mitted to the carriage, but owing to the latter's weight and 
the resistance opposed to the trail spade by its engagement in 
the ground the carriage remains stationary. 

Weights and Dimensions. 

Weight of gun and carriage complete 2,520 lbs. 

Width of track 60 inches 

Length of recoil on carriage 45 inches 

Amount of traverse of gun on carriage 140 mils 

. Nomenclature of important parts of the Gun Carriage :— 

Axle Spade 

Trail, consisting of — Spade edge 

Flasks (right and left) Float 

Tool box Handspike fulcrum 

Elevating gear transom Cradle, head, rear 

Rear sight box Gun slides or Guide Rails 



THE 3-INCH FIELD GUN. 



71 



Cradle Pintle 

Traversing lug 

Rear clip 

Lug for elevating and travers- 
ing lock 

Bracket seat, firing handle 

Quadrant fastening 

Rear-sight bracket support 

Front-sight bracket support 

Spring-support guides 

Retaining ring, with hasp and 
fastening 

Cradle head, front 

Shoulder guard 

Cradle brush 

Recoil-indicator throw 

Recoil indicator- 
Cylinder head 

Cylinder with cylinder end 
screwed in 

Cylinder end stud and nut 

Counter-recoil buffer 

Rings, packing 

Gland 

Piston rod, with plug, screwed in 

Piston 

Piston-rod nut 

Filling plug with gasket 

Drain plug 

Spring support 

Counter-recoil springs 

Rocker 

Cradle Pintle socket 

Elevating and traversing lock 

Traversing mechanism, consist- 
ing of — 

Traversing-gear case 

Traversing plate 

Handwheel with handle and 
spindle 

Traversing shaft 



Traversing-shaft bearing in 
two parts 

Traversing link with bushing 

Traversing-link pivot with nut 

Azimuth pointer and scale 
Elevating mechanism, consist- 
ing of — 

Elevating pin 

Inner elevating screw 

Outer elevating screw 

Wheels guards 

Trail handles 

Trail seats 

Trail-seat supports 

Sponge-staff socket 

Name plate 

Handspike 

Lunette 
Cradle, consisting of — 

Cradle body 

Elevating bevel gear 

Elevating bevel pinions 

Elevating crank shafts, with 
handles 

Elevating screw cover 
Axle seats, include — 

Seat arms 

Seat-arm guards 

Foot rests 

Tie rods 

Shield braces 
Apron shield 
Apron latches 
Main shield, consisting of — 

Main shield 

Hood 

Shutter, open-sight port 

Shutter, panoramic- sight port 
Top shield, consisting of — 

Top shield 

Top shield fastenings 



72 



FIELD ARTILLERY MATERIEL. 



Road brake, includes — 

Brake beams 

Brake shoes 

Springs with covers 

Brake rods 

Brake lever 

Brake shaft 

Brake segment with two seg- 
ment racks 
Ammunition carriers 
Range quadrant case 
Panoramic sight case 
Front sight 
Rear sight, consisting of — 

Rear-sight bracket with shank 
socket 



Rear-sight shank 
Panoramic sight 
Range quadrant 
Wheels, consisting of — 

Felloe, segments 

Spokes 

Tires 

Hub boxes 

Hub liners 

Hub-latch plungers 

Oil Valve 

Carriage bolts and nuts 

Hub bands 

Hub caps 

Wheel fastenings 

Plugs 



THE 3-INCH GUN (CAISSON) LIMBER. 

The limber is of metal throughout excepting the spokes 
and felloes of the wheels. The principal parts are the wheels, 
axle, pintle, frame, ammunition chest, pole, doubletree, 
singletrees, and neck yoke. 

The wheels and wheel fastenings are the same as, and 
interchangeable with those used on the carriage. Seats for 
three cannoneers are provided by a perforated metal bucket- 
holder on top of the chest. The paulin issued to each limber 
serves as a seat cushion and is held in place by paulin straps. 
Grip straps are also provided for use by the cannoneers when 
the carriage is moving at rapid gaits. On the sides and front 
of, and under the ammunition chest, suitable straps, brackets 
and connections are provided for securing all tools and ac- 
cessories. With each limber are issued three tubular oil cans, 
each in the form of a cartridge and with a capacity of two- 
thirds of a gallon. These are intended to hold hydroline, 
lubricating and coal oil and are carried in the central row of 
cartridge holes in the ammunition chest. 



74 



FIELD ARTILLERY MATERIEL. 



Weights and Dimensions. 

Weight of limber, completely equipped and loaded . . 1740 lbs. 
Weight of gun, carriage and limber, completely 

equipped and loaded 4260 lbs. 

Number of rounds carried 36 



Nomenclature of important 
Pole, complete, consisting 
of— 

Pole body 

Neck-yoke counter stop 

Neck-yoke stop 

Neck-yoke chafing plate 

Butt reinforce 
Doubletree 
Doubletree rods 
Name plate 
Limber prop 
Foot rest 
Tie-rods 
Pintle with bearing, consisting of- 

Pintle 

Pintle latch 

Pintle latch spring 
Wheels and wheel fastenings 
Axle 

Middle rail 
Side rails 



parts of limber: — 

Ammunition chest, consisting 
of— 

Hand rail 
Door chains 
Shot bolts 
Bucket holder 
Chest rails 

Chest-rail connections 
Body 
Door 

Cartridge holes 
Diaphragms 
Lantern brackets 
— Grip-straps 
Paulin straps 
Various tool brackets 
Various tools 
Paulins 
Picket ropes 
Lanterns 
Canvas buckets 



THE CAISSON 

The Caisson is made of metal throughout with the ex- 
ception of the spokes and felloes of the wheels. The principal 
parts are the wheels, axle, pintle, lunette, apron shield, fuze 
setter bracket, frame, road brake, and ammunition chest. 

The wheels and wheel fastenings are interchangeable 
with those of the gun carriage and the limber. The caisson 
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THE 3-INCH FIELD GUN. 75 

as far as possible being interchangeable. The frame upon 
which the ammunition chest rests, is diamond shaped, and 
consists principally of two steel side rails riveted to lugs on the 
axle, meeting in front to form the lunette for attachment to 
the limber, and in rear to form a pintle for attachment of 
another caisson in case it is desired to tow several caissons by 
one team and limber, as for instance in the ammunition train. 
In other respects the construction is similar to that of the 
limber excepting that the ammunition chest is much larger and 
has a capacity of 70 rounds. The front of the chest and the 
chest door are made of armor plate. A bracket for the fuse 
setter is also provided. An apron shield, similar to the one 
on the gun carriage is hinged under the axle, giving the can- 
noneers at the caisson full protection. A spare-pole body 
can be carried under the caisson frame, large end of pole to the 
front. On the sides and front of, and under the ammunition 
chest, suitable straps, brackets and connections are pro- 
vided for securing all tools and accessories. To lock the cais- 
sons and limbers, a padlock is provided. These locks are 
interchangeable and can be unlocked by the same key. This 
key is marked " Ammunition." 

Weights and Dimensions. 

Weight of caisson only, completely equipped and 

loaded 2820 lbs. 

Weight of caisson and limber, both completely 

equipped and loaded with 106 rounds 4560 lbs. 

Number of rounds of ammunition carried in caisson only .... 70 

Nomenclature of important parts of Caisson : — 

Wheels Side rails 

Wheel fastenings, complete Pintle with bearing,consisting of — 

Axle Pintle 

Middle-rails Pintle latch 



76 



FIELD ARTILLERY MATERIEL. 



Pintle-latch spring 
Name plate 
Channel supports 
Frame handles 
Lunette, with nut 
Caisson prop, with chains 
Road brake, consisting of — 

Brake-beams 

Brake shoes 

Brake rods 

Brake-rod springs and covers 

Brake shaft, with two keys 

Brake segment 

Segment rack 

Brake lever 
Spare-pole fastening 
Ammunition chest, consisting 
of— 

Diaphragms 

Grip-straps 



Paulin-straps 

Chest rails 

Foot rest 

Handrails 

Door props 

Door handles 

Hand rails 
Supports and Brackets for at- 
taching various tools and 
accessories 
Apron 

Apron latches 
Fuze-setter bracket 
Fuze-setter latch 
Fuze setter 
Paulin 
Picket ropes 

Various tools and accessories 
Spare pole 



To Dismount and to Assemble Parts of the Gun and Carriage. 

To dismantle and to assemble the breech mechanism. — 

Grasp the operating lever and open the breech ; when the block 
is open, force the block latch out of its seat in the block by 
gently pressing it into its seat in the carrier. Take hold of the 
block and revolve it to the left until it stops; then pull it to 
the rear, taking care not to drop it. The block latch can now 
be readily removed. After the firing-lock case has been re- 
moved the operating lever can be removed by forcing its 
pivot up from beneath by a gentle pressure from the palm 
of the hand. The lever latch can be removed by pressing 
in on the latch at a point hear its lower end opposite its 
pivot; a hole in the latch is cut eccentric with reference to 
the pivot and a shoulder on the pivot prevents their displace- 
ment until the latch is forced in and the hole is concentric 
with the pivot. When this occurs, the pivot can be readily 



THE 3-INCH FIELD GUN. 77 

pulled out and the latch removed. To remove the block 
carrier force the hinge pin up by hand until it can be caught 
by the head, and by swinging the carrier back and forth, if 
the pin sticks, it can readily be removed, taking care not to 
drop the extractor lever. The extractor can now be removed 
from the gun. 

To dismantle and to assemble the firing-lock case and 
mechanism. — Take hold of the milled headed locking bolt 
situated at the lower end of the firing-lock case, pull it to the 
rear; at the same time revolve the firing-lock case upward 
about 45° and pull it gently to the rear. This will remove 
the case with the firing mechanism complete from the gun. 
Press the trigger-shaft detent until it disengages from the 
notch in the firing-lock case. This will allow the trigger shaft 
with its detent, to be withdrawn. Then gently press on the 
front end of the firing pin, forcing it back into the casing. This 
will allow the trigger fork to fall out. Then, with one finger 
placed on the front end of the sear, force it outward; at the 
same time grasp the front end of the firing pin, which is 
roughened for the purpose. Give it a sharp pull. This will 
remove the firing-pin spring and sleeve from the casing. 
Then place the front end of the firing pin against a block of 
wood, bear down on the firing-spring sleeve until the spring is 
compressed sufficiently to disengage the slot in the rear end 
of the sleeve from the small lug on the rear end of the firing 
pin; slightly turn the sleeve, and then the sleeve can be sep- 
arated from the spring and pin. By an unscrewing motion the 
spring can be removed from the pin. The sear can be re- 
moved by gently pressing it in toward the center of the casing. 

To assemble, reverse these operations, taking care before 
driving too hard on the end of the trigger shaft that the square 
hole in the trigger fork is in position to receive the tapered 
end of the trigger shaft. No tools are required for assembling 
or dismantling this mechanism. 



78 FIELD ARTILLERY MATERIEL. 

To remove the recoil indicator. — The ends of the clips 
of the recoil-indicator guide are bent down to form stops to hold 
the indicator in place. To remove the indicator, these parts 
are opened up sufficiently to permit sliding the indicator 
out of the guide. When the indicator is assembled, these 
clips should always be closed down to prevent its loss. 

To dismount the gun. — Elevate the muzzle slightly. 
Remove the recoil indicator throw, unscrew the cylinder-end 
stud nut, and shove the gun to the rear until the clips are free 
from the guides. As the gun slides off the cradle, it must be 
properly supported. For this purpose, from 6 to 8 men work- 
ing in pairs with lifting bars are required. 

To mount the gun. — Depress the muzzle slightly. Shove 
the piece from the rear over the cradle guides with the clips 
engaging the guides. Assemble the cylinder-end stud nut, 
taking care that the locking stud on the recoil lug enters one 
of the recesses provided for it in the end of the cylinder. 
Assemble the recoil indicator throw. The dust guard should 
be assembled with the gun. 

In moving the gun on or off of the cradle particular care 
must be taken to support the breech end so that the gun clips 
remain in line with the gun slides. The firing shaft is also 
quite liable to injury during this operation, and care should be 
taken to prevent its being struck by the nozzle of the gun 
or by implements in the hands of the cannoneers. The cradle 
should be placed at the desired elevation and azimuth before 
beginning either of these operations and not changed during 
its progress, since the working of either the elevating or tra- 
versing mechanisms when the gun is only part way in battery 
brings an excessive and unnecessary strain and wear upon those 
parts. 

To dismount the cylinder. — Bring the gun to approxi- 
mately zero degrees elevation; unscrew the cylinder-end stud 



THE 3-INCH FIELD GUN. 79 

nut and the piston-rod nut; remove the cradle head, front. 
The cylinder is now free and may be pulled out to the front. 

To assemble the cylinder in the cradle. — The counter- 
recoil springs and the retaining ring being in assembled 
position, shove the cylinder (turned so that the drain plug in 
cylinder head comes on top) into its seat from the front, with 
the projecting stud on the recoil lug of the gun entering one of 
the recesses provided for it in the cylinder end; assemble the 
cradle head ; screw in place the piston-rod nut and cylinder-end 
stud nut. 

Be sure that the projecting stud on the gun enters one of 
the holes for it in the cylinder end before screwing the cylinder-end 
stud nut up all the way. 

To assemble the parts of cylinder after cleaning. — The 

parts should be reassembled immediately after cleaning and 
inspection, and the cylinder filled with hydroline oil issued 
for that purpose. The piston should be moved back and 
forth in the cylinder by hand to make sure that all parts 
are correctly assembled and are without interference. The 
cylinder should then be assembled in the cradle and the 
gun pulled from battery by hand and permitted to counter 
recoil rapidly to insure that all parts are in proper posi- 
tion for firing. This should never be done, however, unless 
the cylinder is known to be filled with oil. In reassembling the 
parts the condition of the vulcanized-fibre washers between 
cylinder head and cylinder, and between cylinder-end stud and 
cylinder end should be noted; they should be replaced when- 
ever necessary to prevent leakage. In removing and insert- 
ing the piston rod care should be taken to keep it central in 
the cylinder, so as not to bind, burr, or spring any parts. 
The dismounting and reassembling of the parts of the cylinder 
should in every case be supervised by a commissioned officer. 
Before firing an inspection should be made to ascertain that 



80 FIELD ARTILLERY MATERIEL. 

the different parts, especially the piston rod and the cylinder- 
end stud nuts, are correctly assembled. 

To pack the stuffing box. — The stuffing box is packed 
with five rings of Garlock's hydraulic waterproof packing, 
0.25 inch square. The packing is issued cut into rings of such 
size that the ends meet around the piston rod. The latter 
being assembled, each ring, placed so as to break joints with 
the preceding one, is forced in succession into its seat by a 
packing tool of copper or hard wood, one end of which is 
shaped like a carpenter's gouge and the other end forms a 
handle strong enough to stand light taps from a hammer. 
Such a tool may be readily improvised by one of the battery 
mechanics. After the five rings are firmly seated in the box, 
screw the gland down on the packing. 

In assembling the glands be sure that at least four of its 
threads are engaged with the threads of the cylinder head; 
otherwise the threads of the gland may be stripped in firing. 
With new packing it may be found difficult to insert more than 
four rings and secure sufficient engagement of the gland. In 
in such a case the box should be packed with four rings and 
the piece fired a few rounds, after which the fifth ring should be 
inserted. 

Adjustment of the gland. — The adjustment of the gland 
will require the exercise of some judgment. If screwed up too 
tight, the frictional resistance of the packing on the piston 
rod will be increased so much that the counter-recoil springs 
may fail to return the gun to battery, especially at high angles 
of elevation. It should be screwed up just tight enough to 
prevent the leakage of oil through the stuffing box. Ordinarily 
this can be done by hand, but in cases where hand power is 
not sufficient the wrench provided for the purpose should be 
used. When its proper adjustment is determined, the gland 
should be lashed with copper wire to prevent it from screwing 
up or unscrewing. 



THE 3-INCH FIELD GUN. 81 

To remove the piston rod. — Unscrew the gland sufficiently 
to release the pressure of the packing upon the rod; unscrew 
and remove the cylinder head. The rod may then be with- 
drawn from the cylinder. In dismounting and assembling the 
cylinder head (and also the cylinder-end stud), the cylinder 
should be held from turning by a spanner applied to the head 
retainer or flange on the front end of the cylinder. It should 
never be clamped in a vise, as its walls are thin and not intended 
to withstand such usage. 

To remove the counter-recoil buffer. — Remove the cylin- 
der-end stud screw; unscrew and remove the cylinder-end 
stud ; the counter-recoil buffer is attached to the latter. 

To dismount the springs. — Bring the gun to approxi- 
mately zero degrees elevation; unscrew the cylinder-end stud 
nut and the piston-rod nut; shove the gun about 1 inch from 
the battery ; attach the sleeve end of the spring compressor to 
the cylinder-end stud and put sufficient strain on the compres- 
sor to relieve the retaining ring from spring pressure; then re- 
move retaining ring (and cradle head) by loosening and swing- 
ing aside the retaining-ring bolts; ease off slowly on the spring 
compressor until the springs are free. 

To assemble the double counter-recoil springs. — With 
the cradle at maximum elevation and the trail horizontal, 
place one outer and one inner spring in the cradle until the 
front ends are about 2 inches in; set up a separator against 
the forward end of these sections and enter the second outer 
and inner springs, keeping the separator upheld between the 
sections; similarly when the outer end of the second section 
is 2 inches inside the cradle set up the second separator; 
place the third outer and inner sections on the recoil cylinder. 
Screw the spring centering tool onto the cylinder-end stud, 
the small end pointing rearward; pass the sleeve end of the 
spring compressor through the gun lug and the inner springs 

T. B.— 6. 



82 FIELD ARTILLERY MATERIEL. 

and attach it to the cylinder-end stud. Enter the rear end 
of the cylinder in the spring at the front end of the cradle 
and push the cylinder back until the^prings are at free height, 
keeping the spring compressor taut. Attach the block and 
fall carried in the battery wagon to the spade of the car- 
riage or to some improvised support and connect it to the 
spring compressor; put sufficient strain on the spring com- 
pressor to bring the spring column to its assembled height. 

As the spring column approaches its assembled height 
the spring support must be turned so that its guide lugs prop- 
erly enter in the spring-support guide grooves in the cradle; 
assemble the retaining ring, disconnect the spring compressor 
and the spring centering tool from the cylinder-end stud; 
push the gun back into battery and assemble the cylinder-end 
stud nut. When the retaining ring is assembled the nuts for 
the retaining ring bolts should be screwed up until they just 
come into contact with the retaining ring. If these nuts are 
screwed up too tight they will deform the retaining ring, with 
the result that it becomes difficult to assemble and dismount 
the cradle head. A wrench is provided for turning the spring 
support to its proper position. 

To assemble the single counter recoil spring. — The same 
method is followed except that no separators are used. 
The spring compressor is provided with a second eye at 
its large end which may be used in case the sleeve end should 
become broken; in case this end is used, however, it will be 
necessary to pass the compressor through the cradle from 
front to rear, through the gun lug. For disconnecting the 
compressor the method used is identical to that previously 
described. 

The cylinder-end stud nut should never be removed when the 
gun is at an elevation, and the gun should not be elevated when 
the cylinder-end stud nut is not in place. To prevent the 
cylinder-end stud from rotating a screw for the cylinder end 



THE 3-INCH FIELD GUN. 83 

is provided. This screw for the cylinder end must be removed 
before attempting to unscrew the cylinder-end stud. 

Since the springs are assembled under an initial load of 
over 750 pounds, a pull of more than 750 pounds must be 
exerted upon the spring compressor in assembling them. 
This can be done by passing a handspike through the loop at 
the rear end of the compressor and making use of the serv- 
ice of the entire gun squad, or the block and tackle may be 
used as described above. To avoid the possibility of injury 
to the gun squad in compressing or releasing the springs, all 
should be required to keep arms and bodies away from the front 
of the spring column during these operations. 



84 FIELD ARTILLERY MATERIEL. 



CHAPTER VI 
FRENCH 75 

GUN. 

Weights and Dimensions. 

Weight 1015 lbs. 

Total Length (about) 107 in. 

Rifling . 24 grooves 

Twist — right-hand slope, 7 degrees, 1 turn in 25.6 calibers. 

CARRIAGE. 

Weights and Dimensions. 

Weight complete 1642 lbs. 

Weight of gun and carriage complete 2657 lbs. 

Weight at end of trail, carriage limbered 114 lbs. 

Diameter of wheels 52.5 in. 

Length of recoil . . .* (about) 45 in. 

Maximum angle of elevation (338 mils.) 19 degrees 

Maximum angle of depression . (178 mils.) 10 degrees 

Amount of traverse of gun on carriage. . (106 mils.) 6 degrees 

The gun is of the built-up type and consists of a forged 
steel tube which extends from muzzle to breech. A breech 
hoop is shrunk over the rear of the tube and extends beyond it 
to provide a breech recess. This recess is threaded with 
seven threads to take the breechblock. A bronze jacket en- 
circles the central portion of the tube. Inner and outer locking 
hoops screw to and firmly fasten the tube, hoop and jacket 
together and prevent them from separating under the stresses 
of recoil. A muzzle hoop is screwed on the tube at the end 
of the muzzle. 



FRENCH 75. 87 

A recoil lug on the under side of the breech hoop forms a 
point of attachment between gun and recoil mechanism 
through the media of a piston rod and coupling key. 

The rear sight is attached to the rear portion of the 
breech hoop. On top of the hoop at its rear end are two 
quadrant seat plugs. The front sight is fixed on top of the 
rear end of the jacket. A sweeper plate which sweeps and 
lubricates the roller is secured to the front end of the jacket. 

The breechblock is the Nordenfeld rotating type, cylin- 
drical with seven threads which serve to screw it into the 
rear of the breech. The breech is opened and closed by rotat- 
ing the block 120 degrees around its axis. The block advances 
during the rotation due to the pitch of its threads and forces 
the cartridge case into the bore. The gun cannot be fired until 
the block has been completely closed, a condition which must 
exist before the striker of the firing mechanism is in line with 
the primer cartridge of the projectile. 

The extractor consists of three parts : 

1. Two arms connected by a hollow shaft. 

2. A spindle which passes through the shaft and fastens 
it to the breech. 

3. An extractor tang. 

The action of the extractor is as follows : When the breech 
is closed the arms of the extractor are pressed against the face 
of the tube by the rim of the cartridge case which bears against 
them. The extractor tang projects into a groove in the inner 
face of the breechblock known as the loading groove. This 
groove is circular and its depth is equal to the projection of the 
extractor tang. It terminates in a helical guide surface called 
the "ejecting ramp." 

The first part of the movement of opening the breech 
serves to move the grooves in front of the extractor tang. 
This pressure forces the extractor tang back into its slot in the 



FRENCH 75. 89 

breech hoop and as the extractor tang is firmly seated in the 
extractor, the arms of the latter are rotated around the ex- 
tractor spindle. The arms being brought to the rear, press 
against the rim of the cartridge case, which is thereby started 
and ejected. 

Inversely (the breech being open) when a cartridge case 
is smartly inserted in the chamber the rim carries the arms 
of the extractor forward. The extractor tang is thereby forced 
against the beveled surface of the ejecting ramp and auto- 
matically starts the closing movement of the breechblock. 

A safety catch is provided to keep the breech locked be- 
between the time that the breech is closed and the shot is 
fired. 

The firing mechanism consists of a striker or firing pin 
seated in the breechblock, a firing hammer, firing rack, spring 
and lanyard. By pulling the lanyard the hammer is drawn 
back and the rack moves forward against the compression 
of the spring due to its being geared to the hammer. When 
the lanyard is released, the spring forces the rack back which 
in turn causes the hammer to fly forward and strike the primer. 
A safety device is provided for locking the hammer while the 
piece is in the traveling position. 

THE CARRIAGE. 

The gun is mounted upon a cradle which encloses the 
recoil and counter-recoil mechanisms. The device for elevat- 
ing the gun through the angle between the horizontal and the 
line gun-target (angle of site) is interposed between the trail 
and the rocker while the device for giving the gun elevation 
for range is placed between the rocker and the cradle. This 
arrangement is known as the independent angle of site or in- 
dependent line of sight. It has the advantage over the three- 
inch type in that it allows the range elevation to be altered 
without disturbing the elevation for site. 









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FRENCH 75. 95 

The principal parts of the carriage are: trail, axle, wheels, 
brakes, shields, angle of site elevating mechanism, range 
elevating mechanism, traversing mechanism, rocker, cradle 
and sights. 

When traveling or resting, the tube rests on the cradle 
which supports it by means of the jacket. When firing, it 
recoils on the cradle by means of the rollers. The jacket has 
two pairs of rollers, and the muzzle hoop is provided with a 
single pair of rollers. On the upper part of the cradle are the 
lower slides, on which the jacket rollers, supporting the tube, 
roll during the recoil. When the jacket rollers are about to 
leave the lower slides, the muzzle rollers come under the upper 
slides; the tube is then supported until the end of the recoil 
by the muzzle rollers and the more forward of the two pairs 
of jacket rollers. This device gives the gun a long recoil upon 
short slides. Inclined planes are used in such a manner that 
when the gun returns into battery the rollers rise from the 
lower slides thereby relieving the slides from the weight of 
the tube when the tube is in the traveling position. 

The carriage supports the cradle which in turn supports 
the tube. The cradle and the tube together are displaced, 
during the laying for elevation with respect to the carriage 
which remains stationary. The carriage is held steady on the 
ground by means of the trail spade which with abatage pre- 
vents the carriage from recoiling on the ground. 

Abatage consists of elevating the wheels on the brake 
shoes which are provided with small spades which prevent 
lateral movement. The brake shoes are fastened to brake 
beams attached to a sliding rack beneath the trail in such a 
manner that the abatage frame may be placed under the car- 
riage during travel. In preparing to fire, the frame may be 
adjusted to allow the brake shoes to slip from a position in 
rear of the carriage wheels to a point directly beneath the 
wheels. 



FRENCH 75. 97 

Abatage is accomplished as follows: (1) The brake shoes 
are dropped to the ground in rear of the point of contact of the 
wheels with the ground; (2) The trail is lifted, turning around 
the axle, until the spade is about five feet in the air. Tie 
rods and a slide working on a rack beneath the trail move 
forward in this action; (3) The trail is then brought down. 
The rack prevents the slide from moving to the rear and the 
carriage turns on the abatage frame until the wheels rest upon 
the brake shoes. This gives the gun a three point support, 
two small spades under the wheels and a larger one at the 
end of the trail. 

Laying in direction is accomplished by traversing the 
piece on the axle. The trail spade is fixed and the axle is 
straight and rigid so that in the movement of the gun to the 
right and left on the axle both wheels must turn — one to the 
front and one to the rear. The device for laying for direction 
is composed of a threaded axle, which is prevented from 
rotating by a spur and a sliding nut which is contained in a 
box fixed on the left flask of the gun. This nut bears one of 
the bevel gears, which is put in motion by the hand wheel. 
The traverse is three degrees either side of the center or a total 
of 6 degrees or about 105 mils. 

Laying for elevation. To obtain greater accuracy and 
speed in firing the 75 has an independent angle of site. A 
rocker with two trunnions is interposed between the cradle 
and the carriage. The rocker trunnions are seated in the 
cradle trunnions and support them. This gives the same ro- 
tating axis to both rocker and cradle. This is necessary for the 
mechanical addition of the angle of site elevation and for the 
range elevation. When the angle of site handwheel is re- 
volved it turns a pinion, which meshes in the rocker rack and 
thus causes the rocker to move in relation to the carriage. 
This gives the cradle through the rocker the elevation equal 

T B— 7 




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FRENCH 75. 99 

to the difference in elevation between the target and the 
gun. It is independent of the angle given to the gun for the 
elevation due to range to the target. 

The angle given the gun for range is effected through a 
telescopic screw. This screw is fastened at one of its extrem- 
ities in the rocker and at the other in the cradle. The nut 
which receives the elevating screw is seated in an oscillating 
support which allows it to always remain perpendicular to the 
axis of the bore at any elevation. 

The angular displacements of the cradle with respect to 
the rocker (angle of elevation) are recorded by the elevating 
system composed of a graduated arc and a range drum. The 
lower part of the arc is connected with the right arm of the 
rocker. The arc is graduated in meters. When the range 
handle is turned the arc does not move, but a brass slide block 
connected with the gun and the cradle and bearing an index 
slides along the arc. It is thus possible to set the range in 
meters. 

However, the arc graduations are not very legible and 
it has been supplanted by a graduated range drum having 
more legible readings. 

The black part of the arc bears a rack which meshes 
with a pinion, which in turn rotates around an axle fixed on 
the cradle. When the cradle moves, the pinion rotates and 
carries with it the range drum. 

The elevation on level ground varies from a minus 11 
degrees to a plus 20 degrees. Greater elevation may be ob- 
tained by sinking the spade. 

The Recoil and Counter-recoil mechanisms are of the 
Hydro-pneumatic type. Their accurate description is a 
secret. The following brief description will give only a general 
idea of the working of the mechanism. The whole apparatus 
is inside of the cradle through which are bored two cylinders : 
an upper cylinder 40 mm diameter, and a lower cylinder 66 



100 FIELD ARTILLERY MATERIEL. 

mm diameter. These cylinders may communicate through 
a large hole. A piston moves in the upper cylinder, the piston 
rod, 24 mm diameter, being fast to the gun. 

In the lower cylinder are: (1) The valve carrier pipe 
screwed in the rear part of the cylinder supporting spring 
valves; in the inner walls of the pipe are cut two grooves; 
the valve carrier pipe is ended by a circular ring. (2) The 
diaphram with its hollow rod. (3) The loose piston with its 
small rod, which may come in contact with the upper rack of 
the gauge. The two cylinders are full of liquid, usually Russian 
oil. The front part of the upper cylinder in front of the piston 
may communi?ate freely with the air through the Front Plug. 
The front part of the lower cylinder is closed by a plug and 
contains compressed air at a pressure of 150 kg. per sq. cm. 

Operation. In recoil the piston of the upper cylinder 
compresses the liquid, which has to pass through the spring 
valves and between the circular ring and the hollow rod of the 
diaphragm. The passage of the liquid through these different 
openings constitutes the braking effect. In so moving the 
liquid opens the valves, which are widely opened at the be- 
ginning of the recoil and gradually close in proportion to the 
decrease of the speed of the recoil. At the same time, the air 
of the recuperator is compressed by the action of the liquid 
on the diaphragm. 

When the recoil is finished, the compressed air pushes 
back the diaphragm. The liquid thus compressed acts 
on the small cylinder piston and obliges it to come back into 
its initial position, bringing with it the tube. 

The liquid in flowing back completely closes the valves 
and must pass between the diaphragm rod and the inner wall 
of the pipe. At beginning of the return into battery, the 
space between the rod and the bottom of the groove is large. 
This space decreases in proportion to the progress of the re- 
turn. The passing of the liquid through this constantly de- 



FRENCH 75. 101 

creasing space causes the braking which at the end reduces the 
speed of the return to nil. 

CARE AND PRESERVATION OF FRENCH 75. 





Dismountings. 


Canoneer Dismounting^. 


A. 


Breechblock. 




1. Safety piece. 




2. Striker. 




3. Lanyard. 




4. Striker hammer. 




5. Hammer spindle. 




6. Spring assembling pin. 




7. Rack springs. 




8. Rack. 




9. Latch pin. (Pawl Pin.) 




10. Latch (Pawl). 




11. Latch spring. (Pawl spring.) 


B. 


Extractor. 




1. Clow. (Tang.) 




2. Spindle. 




3. Arms. 


C. 


Level. 


D. 


Sight case. 


E. 


Wheels. 


F. 


Limber pole. 


G. 


Fuze setter from caisson. 


H. 


Luggage frame from limber. 


Mechar 


dc Dismountings. 


A. 


Coupling keg. 


B. 


Push gun back on slides. 


C. 


Safety bolt. 


D. 


Friction piece. (Sweeper plate.) 


E. 


Wiper. (Guide piece.) 


F. 


Front plug. 


G. 


Filling hole plug. 


H. 


Elevating screw pin. 



102 FIELD ARTILLERY MATERIEL. 

I. Elevating screw. 
J. Trunnion caps. 

K. Rocker Trunnion caps. (Half Rings.) 

Daily Cleaning and Lubricating. 

(By cannoneers.) 

1. Clean sight support and socket. 

2. Lubricate oil holes 20, 21, 22, 23, 24. 

3. Clean base of sight column. 

4. Clean levels. 

5. Lubricate range mechanism. (Holes Nos. 1 and 2.) 

6. Clean and oil rocker trunnion caps. 

7. Oil holes 7 and 8. 

8. Clean and grease exposed parts of axle. 

9. Dismount and clean breech and all its parts. 

10. Clean and grease the bore if the gun has been fired. 

II. Clean and grease the slides if the gun has been fired. 

12. Grease the wheels if the gun has been on the road. 

13. Clean fuze setter. 

14. The life of a gun depends on "Daily Care." 

Forbidden Practices. 

1. Readjustment of French Sights, 

2. Fitting with files, 

3. Forging and Riveting, 

4. Unauthorized Dismountings, 



Care of Recoil Mechanism, 

(Chief Mechanic Only) 

Caution. — Never remove piston rod nut, as piston is 
under pressure and would pull piston rod into cylinder. 

The recoil apparatus proper cannot be dismounted. 

If properly taken care of the recoil mechanism will not 
go wrong for years; but if neglected, its destruction is only 
a matter of very little firing. 

The position of the gauge finger is the index as to whether 
or not the recoil is being properly absorbed. 



FRENCH 75. 103 

The joints are not absolutely tight, the slight leakage 
which takes place during fire or even when gun is at rest is 
not important. 

In normal firing conditions the recoil apparatus contains 
a slightly greater quantity of oil than absolutely necessary; 
this quantity is called the "reserve." When the reserve is 
exhausted any loss is liable to reduce the quantity strictly 
necessary. The loss may prevent the gun from fully return- 
ing to battery when firing. 

The amount of reserve is indicated by the position of the 
gauge. 

No reserve: The gauge finger is down deep in its recess. 

Full reserve : The end of the gauge finger is level with the 
gauge index. 

Excess reserve : The gauge finger projects beyond the index. 

No firing should be done with an excess reserve. 

The gauge finger should be between the index and 1/8 inch 
below the index. 

It is the duty of the Chief Mechanic to see that the gauge 
finger is in the proper position before firing. 

It is the duty of the Executive and the Chief of Section 
to see that the gauge finger is in the proper position during 
fire; if it moves from this position the Chief Mechanic will 
be called to make the proper adjustments. 

When the gauge finger has been brought to the proper 
position there are only two conditions which call for tampering 
with recoil apparatus. 

1. The gun goes into battery too slowly, or has to be 
pushed in. 

In this case the gauge finger will usually be found too deep 
in its seat, and the pump will have to be used. If the gauge 
is in the proper position look at the slides. Either they will 
be found dirty or bits of the wiper may be nicked off. In 
the latter case the gun can be fired without the wiper. 



104 FIELD ARTILLERY MATERIEL. 

2. The gun jumps badly. In this case the gauge finger 
will generally be found beyond the index. When this is the 
case the oil extractor must be used until the gauge finger is 
in the proper position. 

If after cleaning slides, putting gun in abatage and adjust- 
ing gauge finger, the gun still jumps badly — complete drain- 
ing of the reserve and refilling will frequently remedy the 
trouble. 



75-MM. FIELD GUN, MODEL 1916. 105 



CHAPTER VII. 
75-MM. FIELD GUN MODEL 1916. 
THE GUN. 

Weights and Dimensions. 

Weight Kg 339.74 pounds 749. 

Caliber mm 75 . inches 2 . 953 

Total length mm 2,308.5 inches 90.9 

Length of bore mm 2,134. inches 84. 

Length of rifled portion of 

bore mm 1,847 . inches 72 . 72 

Number of grooves 24 

Width of grooves mm 7 . 30 inches . 2874 

Depth of grooves mm . 501 inches . 02 

Width of lands mm 2 . 52 inches . 0992 

Twist, right hand, zero turns from origin to a point 2.89 
inches from origin. Increasing from one turn in 119 calibers 
at a point 2.89 inches from origin to one turn in 25.4 calibers 
at a point 9.72 inches from muzzle. Uniform from a point 
9.72 inches from muzzle to the muzzle. 

Description of the 75-MM Field Gnu. 

The gun is built up of alloy-steel forgings, consisting 
of a tube, jacket, breech hoop, and clip. All of the parts are 
assembled with a shrinkage. 

The tube extends from the muzzle to the rear end of the 
powder chamber and two recesses are cut in its rear face to 
form seats for the lips on the extractors. 

The jacket is assembled over the muzzle end of the tube. 
The jacket carries two flanges on its lower side, which form 



106 FIELD ARTILLERY MATERIEL. 

guides for the gun in the cradle of the carriage, and a lug on 
top near the forward end which contains a T slot, which holds 
the recoil cylinder in place. The rear end of the jacket is 
threaded on the outside to receive the breech hoop. 

The breech hoop is threaded at its forward end and screws 
on to the rear of the jacket. The breech ring carries a recoil 
lug at the top for the attachment of the hydraulic recoil cylin- 
der, and another lug at the bottom for attachment of the two 
spring piston rods. The rear part of the breech hoop is cut 
away to form the breech recess. 

The clip is a short hoop shrunk on the tube near the 
muzzle. It carries two lugs on its under side which form 
guides for the gun in the carriage. 

The rear ends of the guides on the jacket are extended to 
the face of the recoil lugs by short extensions riveted in place 
to prevent entrance of dust between surfaces of the guides 
and their bearing surfaces on the cradle. For the same pur- 
pose the forward ends of the guides on the jacket are connected 
by steel-plate dust guards with the rear ends of the guides on 
the clip. 

Description of the Breech Mechanism. 

The mechanism is known as the drop-block type, and is 
semi-automatic in design in that the block closes automatically 
when a round of ammunition is inserted. A rectangular hole 
extending through the rectangular section of the breech hoop 
forms seat for the sliding block. The upper part of the breech 
hoop in rear of this slot is cut away, leaving a U-shaped open- 
ing which permits the passage of the cartridge case. 

Recesses cut in both the side faces of the breech recess 
form seats for trunnions for the two extractors. Holes bored 
into these recesses from the rear face form seats for the extrac- 
tor plungers, springs and plugs. The block slides up and down 
in the breech recess under the action of the operating arm 



110 FIELD ARTILLERY MATERIEL. 

which is pivoted on the operating shaft and acts as an oscillat - 
ing crank in raising and lowering the block. The operating 
shaft which rotates the operating arm is actuated by the 
operating handle. The operating handle is provided with a 
latch to keep it in the closed position and is connected by a 
chain, piston, and piston rod to the closing spring, which is 
carried in the closing-spring case. The closing spring is under 
compression and tends to keep the block closed or to close the 
block when it is opened. 

When the block is opened as far as it will go, it is locked 
in that position by the inside trunnions on the extractors. 
These trunnions are forced over horiztonal shoulders on the 
block by means of the extractor plungers and holds the block 
in the open position. When a cartridge is pushed smartly 
into the gun, its rim striking against the lips on the ex- 
tractor frees the trunnions from the shoulders on the block and 
allows the block to close under the action of the closing spring. 

A continuous-pull firing mechanism is carried in the recess 
bored out in the center of the block and is operated by the 
trigger shaft which projects from the bottom of the block. 
This mechanism is cocked and fired by one continuous motion 
of the trigger shaft so that in case of a misfire the primer may 
be struck a second blow by releasing the shaft and rotating 
it again. A lanyard may be attached to the projecting end of 
the trigger shaft. 

CARRIAGE. 
Weights and Dimensions. 

Weight of carriage, complete, fully equipped, with- 
out the gun 2280 pounds 

Weight of gun and carriage fully equipped 3045 pounds 

Weight of lunette, carriage limbered 140 pounds 

Diameter of wheels 56 inches 

Width of track, center to center of wheels 60 inches 



75-MM. FIELD GUN, MODEL 1916. Ill 

Length of recoil of gun on carriage, variable recoil ... 18 to 46 

Height of axis of gun about ground 42 approx. 

Amount of elevation with elevating handwheel. . . .42 degrees 

Total limits of elevation 7 to plus 53 degrees 

Maximum traverse either side of center 400 mils 

Over all width of trails, spread 130 inches 

Over all length, muzzle of gun to end of lunette 173 inches 

Limits of elevation with angle of site handwheel, minus 
7 degrees depression to 11 degrees elevation. 

Description. 

The carriage is of the split trail, variable long-recoil type. 
The length of recoil is regulated automatically, so that the 
breech of the gun will not strike the ground on recoil at an 
angle of elevation of less than 47 degrees. At elevations 
greater than 47° a hole must be dug for the breech in recoil. 

The gun is mounted in slides on a cradle formed by the 
spring cylinder. The spring cylinder is suspended by trun- 
nions mounted in bearings in the top carriage, which is sup- 
ported by the pintle bearing to which are attached axle arms 
bearing in the wheels. 

The carriage has an independent angle of site elevating 
mechanism, by means of which a maximum depression of seven 
degrees and anangle of elevation of 11 degrees may be obtained. 
The remaining elevation is obtained through the elevating 
handwheel. 

The principal parts of the carriage are : 

Trail Elevating mechanism 

Cradle Traversing mechanism 

Recoil mechanism Axle seat 

Top carriage Brake mechanism 

Pintle bearing Shoulder guards 

Equalizing gear Firing mechanism 

Shields Sight, model of 1916 

Angle of site mechanism Wheels. 




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114 FIELD ARTILLERY MATERIEL. 

The trail is made in two halves of box section built of 
bent and riveted steel plate. Each half is bolted to a lug on 
the equalizing gear, so that it may be rotated horizontally 
from the junction point of the trail to the point where the trail 
hits the wheel. 

The trails are locked together in traveling position by 
means of a cone-shaped vertical lug on the lunette bracket 
which fits in a socket in the trail coupling, and is locked in place 
by the trail-coupling latch. Trail-coupling latch has a handle 
and catch with a vertical spindle seated in a socket in the 
lunette bracket. A handle-return spring is assembled around 
the spindle and the latch engages a catch on the trail coupling 
when trails are fixed in the traveling position. Latch is 
opened by moving handle forward. 

Lunette consists of a ring for attaching the carriage to the 
limber and is bolted through the lunette bracket. 

Floats are attached to the bottoms of both trails at their 
rear ends, consisting of flanged steel plates for the purpose of 
increasing bearing area of the trails on soft ground. 

Spade hearings are riveted to rear of the trails and form 
bearings for spades in firing position. Spades are driven 
through the bearings, and their upward movement relative 
to the trails is prevented by spade latch. 

Spade-latch bracket consists of a bronze plate with a 
cylindrical chamber for a spring and plunger and two bearings 
for latch-handle pin. Bracket is riveted to the inside top of 
trail in front of the spade. Spade-latch plunger, with a spring 
assembled around it, is seated in the chamber and the spade- 
latch handle is pinned in the bearing. Top of handle extends 
through the trail and is roughened for use as a foot pedal. 
Lower part of handle engages with the plunger. When the 
spade is driven the plunger is forced into a notch in the spade 
by means of the spring, and the slope on face of plunger al- 
lows a downward movement of the spade and prevents up- 



75-MM. FIELD GUN, MODEL 1916. 115 

ward movement. To release spade the foot pedal on latch 
handle is pressed down, disengaging plunger from spade, and 
the spade is removed. 

Trail handles are riveted to outside of both trails for 
lifting trails. Name plate is riveted to outside lower left 
trail. It is important that the number of carriage on this 
plate be recorded by the officer in charge of the unit to which 
it is assigned and that this number be used as a reference in 
all correspondence. Wheel guards, rear, are plates riveted to 
the outside lower left of both trails for the protection of trail 
bodies against contact with limber wheels on short turns. 
Trail guards are bent plates riveted to the top of trail in front 
of trail-coupling latch to prevent battering of trails by sledges 
used for driving the spades. 

Sponge-staff fastenings are riveted to tops of both trails. 
Sponge staffs are inserted in upper rings of staff fastenings 
and the lower ends are clamped in place. The smallest sec- 
tion of sponge staffs fits in sponge fastenings. 

Sledge fastenings are similar to sponge staff fastenings and 
are riveted to the outside of each trail. Wheel guards (front) 
are plates riveted to the outside of trails near the front to pre- 
vent contact of trails with wheels when the trails are separated. 

Spare parts case is a steel box with a hinged steel cover 
provided with a bolt snap and padlock riveted to the out- 
side of front left trail. This case contains spare parts for 
emergency use. 

Trail seats are made of formed bent plates riveted to the 
tops of trails near breech of gun. Oiler support with springs 
is under the right-hand trail seat. Oiler rests on this support 
and is held in place by springs. 

Traveling lock bar consists of a forged steel bar pinned to 
lock bar bearing on left trail and made to swing across trails 
in traveling position and along left trail in firing position. In 
traveling position the socket in the middle of the lock bar 



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118 FIELD ARTILLERY MATERIEL. 

engages with the traveling lock stud in the bottom of cradle, 
and right end of lock bar is held in lock bar clip on right trail 
by the latch. To disengage the latch for firing, the latch 
handle is lifted and the lock bar swung to fastening in left 
trail, where it latches. 

To lock the cradle, the gun is brought to azimuth and the 
traveling lock pointer on right trunnion cap brought to line 
marked "March." In this position the traveling lock socket 
fits over stud, and the lock is latched. The latch consists of 
a lever pinned at one end to the lock bar with a plunger pinned 
in center extending through the bar with a spring around the 
plunger body to hold the latch in place. 

Trail connections are riveted to front end of trail and 
bolted to equalizing pinions. 

The cradle comprises the spring cylinder with attached 
parts. 

The spring cylinder is below and shorter than the gun. 
It is in the form of two cylinders joined at the center, with 
axes in the same horizontal plane. Above the cylinders are 
the gun ways, parallel to the cylinders, bronze lined, and open- 
ing toward the center line of cylinders. Traveling lock stud 
is bolted through a lug at the rear and below the cylinders. 
Firing-shaft bracket is riveted to the left side and range — 
scale bracket to the right side of the cylinder at its rear end. 
Shoulder guards are pinned in sockets in both firing-shaft 
and range scale brackets to prevent contact of the gun during 
recoil, with the cannoneers. Trunnions are riveted and keyed 
to the cylinder near center. Elevating arc is bolted to lugs 
on the bottom of cylinder at trunnions. Piston-rod bracket 
is riveted to projections on the cylinder above the gun slides 
near the front end. Cylinder cover is pinned to cylinder 
clips, which are riveted to the front of spring cylinder. (Note : 
On some carriages the clips are made integral with the cylin- 
der.) 



120 FIELD ARTILLERY MATERIEL. 

The recoil mechanism is designed for variable recoil, the 
length of which is regulated automatically by the elevation 
of the gun. The following table gives lengths at various eleva- 
tions: (These lengths are based on theoretical calculations. 
Actual lengths of recoil between 8' and 45' elevation are gen- 
erally greater.) 

Elevation. Length of Recoil. 

-7.0 to plus 8.0 degrees. ........ 46 inches. 

-8.0 to plus 16.47 degrees 46 to 28 inches. 

-16.47 to plus 27.20 degrees 28 inches. 

-27.20 to plus 36 . 7 degrees 28 to 18 inches. 

-36.7 to plus 53 degrees 18 inches. 

The breech of the gun on short recoil will strike the 
ground at the level with the bottom of the wheels at an ele- 
vation of 47 degrees or over. 

The recoil mechanism is of the hydraulic spring type, with 
the recoil cylinder mounted above the gun and the counter-recoil 
springs in the cradle below the gun. The recoil cylinder is 
held in place by a slot machined in the gun jacket at the front 
and rests in the cylindrical opening in the gun lug above the 
rear of the gun. It is held in place by the cylinder retainer, 
which screws into the rear cylinder parallel to the center line. 

The recoil valve is a cylinder with a collar at the front end 
and three lands inside and parallel to the bore. Three rows 
of holes are bored at the lands. The recoil valve fits inside the 
cylinder, resting on the lands, and is held in place by a collar 
bearing against the edge of the counterbore in the cylinder 
at the front, while the rear end of the valve bears against the 
inside rear end of the cylinder. 

The piston is screwed and pinned to the piston rod and is 
of bronze, slotted to fit lands and grooves in the recoil valve. 
The piston rod is hollow for almost the entire length. The 
front end passes through the gland in the cylinder head and 
piston-rod sleeve. The front of the recoil cylinder is closed 
by the front cylinder head, which is screwed in place with a 



75-MM. FIELD GUN, MODEL 1916. 121 

gasket. A bronze gland with four rings of 5-16 inch Garlock 
packing prevents leakage around the piston rod. 

The counter-recoil buffer consists of a buffer rod screwed 
into the buffer nut at the rear end of the recoil cylinder, and 
extending through the buffer bushing into the interior of the 
piston rod. The buffer head is screwed and pinned into the 
front end of the buffer rod. The buffer head is of two diam- 
eters and connected by a short cone. The rear end is the 
smaller diameter and is threaded inside to screw over the 
buffer rod. The coned surface contains slots leading to a 
hollow chamber in front. The front end of head is faced and 
provided with a central bearing for valve stem. The bearing 
is supported by webs to main body of guide. Valve stem has 
a stop on rear and a valve screwed to front. Valve is faced 
to seat on front of the bearing, webs and circular face of main 
body of guide. 

The counter-recoil springs are assembled around spring 
rods in spring cylinder. Spring rods fit in gun lug and are 
fixed in place by taper keys driven diagonally through lug 
and rod. The rod is hollow for entire length, except at the 
rear, where the outside diameter is decreased to permit en- 
trance in gun lug. Collars are screwed and pinned to front 
ends of rods. Three coils of inner counter -recoil springs are 
assembled over the spring rod, surrounded by three coils of 
outer springs. Inner and outer springs are coiled in opposite 
direction to prevent nesting, and sets of coils are separated 
by a bronze separator. Rear ends of cylinder are bushed for 
spring rods. 

The operation of recoil mechanism is as follows: 

When the gun is fired it moves back in slides on cradle, 
carrying with it spring rods, buffer rod, recoil cylinder, and 
recoil valve. The piston, piston rod, and spring cylinder re- 
main stationary, being fixed to carriage. 



75-MM. FIELD GUN, MODEL 1916. 123 

The recoil cylinder being full of oil, this oil is forced by the 
piston through holes in recoil valve in front of piston up into 
annular space between valve and cylinder and into space be- 
hind and vacated by the piston. The hydraulic resistance 
caused by forcing the oil through the holes in valve absorbs 
most of the recoil energy of the gun, and the remaining energy 
is taken up by compression of the counter-recoil springs and 
friction. 

When the gun reaches the end of recoil all of the recoil 
energy has been absorbed and the counter-recoil springs acting 
against spring- rod piston force the gun back to battery position. 
The purpose of the counter-recoil buffer is to overcome the 
tendency for gun to return to battery too rapidly, at the same 
time allowing sufficient speed of counter recoil to permit maxi- 
mum rapidity of fire. Buffer action is necessary, as the 
strength of springs required to return the gun to battery at 
high elevations is greater than is required at lower elevations. 

The action of counter-recoil buffer is as follows: 

As the buffer rod moves backward in piston rod the valve 
in buffer- rod head is opened by the pressure of oil in back of 
valve and the vacuum in front, which forces oil into buffer 
chamber in front of the buffer-rod head. At full recoil the 
buffer chamber is full of oil and buffer-rod head is inside the 
rear end of piston rod. When springs force gun back in coun- 
ter recoil, buffer rod moves forward, compressing oil in cham- 
ber and forcing valve closed. This prevents escape of oil 
through valve and forces oil to throttle between outside sur- 
face of buffer-rod head and inside surface of piston rod, offer- 
ing resistance to spring action and thus easing the gun into 
battery. The inside bore of piston rod is tapered at front 
end to increase resistance and obtain desired decrease in 
counter-recoil velocity. 

If guns fails to return to battery after a few rounds of 
rapid firing, it is probably due to expansion of oil. This may 



124 FIELD ARTILLERY MATERIEL. 

be determined and corrected by loosening filling plug. If oil 
spurts out, allow it to run until gun is back in battery. It may 
be necessary to relieve oil two or three times immediately 
after filling. Gun should never be allowed to remain out of 
battery more than 1 inch on counter recoil without determ- 
ining and correcting the cause. 

If gun remains out of battery and the relief of oil does not 
cause it to return, it is due to: 

(a) Weak or broken springs ; (b) piston-rod gland too 
tight; (c) dirt or lack of lubrication in gun slides; (d) distortion 
of gun on gun ways; (e) distortion of piston rod due to im- 
proper counter recoil action. 

The majority of cases are due to (a), (b) and (c). 

(a) Can be determined only by removing springs, and 
should be undertaken only after all other methods have been 
tried. 

(b) Can be determined by loosening piston-rod gland. 
If gland is too tight, gun will return to battery when it is 
loosened. If gland cannot be loosened, piston-rod is probably 
distorted. 

(b) Flood slides with oil, and if possible retract gun and 
examine gun ways and slide for dirt. 

(d) If possible allow gun to cool for 15 or 20 minutes. 
In case of (a), (c) or (d) gun can generally be pushed back 
into battery by hand. 

(e) If piston rod or interior mechanism is distorted, 
mechanism must be disassembled and defective parts re- 
placed. If distortion has occurred, it can generally be identi- 
fied by very rapid counter recoil for round on which gun does 
not return to battery. This may be caused by foreign matter 
in oil causing buffer valve to stick, or by lack of sufficient oil. 
If distortion has occurred, it will be near gland and can gen- 
erally be felt by running hand along rod from bracket to gland. 






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126 FIELD ARTILLERY MATERIEL. 

In case of any improper functioning of recoil mechanism 
during recoil or counter recoil, cease firing until cause has 
been determined and corrected. A piece is out of action when 
recoil mechanism is not operating properly and will almost 
certainly be damaged seriously if further firing is attempted. 

After dismounting any part of recoil mechanism or filling 
recoil cylinder, gun is to be retracted and released to allow 
counter recoil if possible. In performing this test, valve- 
turning mechanism must be disconnected and valve turned to 
correspond to an elevation of carriage of 53° before gun is 
retracted. Gun must not be held out of battery more than 
10 seconds before being released. 

Variable recoil is obtained by varying the area of effective 
throttling holes in the recoil valve. An arm on the trunnion 
cap is connected by means of connecting rod, valve-turning 
arm, valve-turning gear, and a piston-rod gear, to the piston 
rod itself. As the gun is elevated the relation of the cylinder 
to the trunnion changes, causing the piston rod to turn by 
means of the valve-turning mechanism. Slots in the piston 
engage lands in the valve, causing the valve to turn with the 
piston. As the cylinder remains stationary the location of 
the lands inside of the cylinder change with relation to the three 
rows of holes in the valve, and these rows of holes are covered 
to produce variations in the length of recoil. At long recoil 
all the rows are uncovered; at intermediate recoil one row is 
uncovered; and at short recoil two rows are uncovered. The 
setting of the valve in degrees elevation is shown by the scale 
on the piston-rod sleeve and index mark on the edge of the 
piston-rod bracket bushing at the top of the piston rod. 

The top carriage carries trunnions of the spring cylinders 
and rests on pintle bearing. The top carriage bears on the 
circular bronze slides in upper part of pintle bearing and is 
centered on the bronze pintle collar of the pintle bearing. 



75-MM. FIELD GUN, MODEL 1916. 127 

The pintle bearing carries the top carriage, the equalizing 
pinions and the equalizing gear, and is supported by the axle 
arms, which are shrunk in the arms of the pintle bearing. 
Axle arms bear in the wheels. 

The object of the equalizing gear is to increase the sta- 
bility of the carriage in firing when the wheels are at different 
elevations. Equalizing gear is an H-section with bevel tooth 
sector on each end and bronze-bushed bearing in the center. 
It bears over the vertical journal below the pintle bearing and 
is held in place by equalizing-gear support screwed inside the 
journal. Vertical deflection is prevented by the equalizing- 
gear bolts which are fixed to the pintle bearing by means of 
nut and shoulder, pass through slots in equalizing gear, 
and support gear on bolt heads. Equalizing pinions are bevel 
pinions sectors, bronze bushed, bearing over the arms of the 
pintle bearing, and have the lugs for trail connection bolts. 
Pinions are held in place by locking rings screwed over axle 
arms and are free to revolve about the pintle bearing arms. 

Equalizing pinions mesh with equalizing gear. 

When the carriage is laid with wheels at different eleva- 
tions, it is more unstable than when wheels are level. If 
fired under this condition, the force of recoil tends to overturn 
the carriage. The function of the equalizing gear is to over- 
come this tendency. When carriage is fired, firing stresses 
are transmitted to trails, and the side on which the smaller 
stress is exerted tends to rise. This motion is transmitted 
through equalizing pinion and equalizing gear to equalizing 
pinion on other side, applying downward force on this trail 
and preserving the stability of carriage. 

The angle of site mechanism is designed to give the gun 
a maximum depression of about 6° and a maximum elevation 
of 11°, independent of the elevating mechanism. The mech- 
anism is operated by two handwheels, one on each side of 
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75-MM. FIELD GUN, MODEL 1916. 129 

Handwheel on right side operates through bevel gear on 
handwheel shaft and intermediate shaft, both mounted in 
angle of site bracket, right, and cross shaft mounted in bronze 
bushings in top carriage. Handwheel on left side operates 
through bevel gears on handwheel shaft, mounted in angle of 
site bracket, left, and cross shaft mounted in bronze bushings 
in top carriage. Bevel gears on ends of both cross shafts 
mesh with bevel gear on angle of site worm, which is mounted 
in bushings in top carriage and held in place by angle of site- 
worm caps. This worm meshes with teeth cut in rocker. 

Rocker is a U-shaped piece with bearings at the tops of 
both arms and teeth cut in bottom of U. The bearings bear 
over and are free to revolve about trunnions on cradle inde- 
pendent of trunnion bearing in top of carriage. Top half of 
right bearing is formed by rocker arm, right, which extends 
•back and carries angle of site scale, pointer, rack, and level 
and forms a bearing for elevating handwheel shaft. Rear 
of rocker arm, right, is braced by rocker arm brace, a diagonal 
hollow rod attached to rocker arm and rocker. Top half of 
left bearing is formed by rocker arm, left, a diagonal arm ex- 
tending upward to the rear to form a support for sight. Move- 
ment of the angle of site mechanism is limited in elevation by 
the rocker stop bolted to the side of the rocker and in depres- 
sion by a screw in the arc. 

The elevating mechanism is designed to allow an eleva- 
tion of the gun of 42° independent of the angle of site mechan- 
ism. The mechanism is operated by one handwheel on the 
right side of carriage, which is turned in a clockwise direction 
to elevate gun. 

The elevating mechanism is operated through bevel 
gears on elevating handwheel shaft mounted on a rocker arm, 
right, elevating intermediate shaft inside rocker-arm brace, 
elevating cross shaft, mounted in an elevating cross-shaft 
bearing bolted to the rocker, and the elevating worm, which 

T. B.— 9 



75-MM. FIELD GUN, MODEL 1916. 131 

bears inside lower part of the rocker. The elevating worm 
meshes with the elevating arc, which is bolted to the bottom 
of the spring cylinder. 

In indirect fire the angle of site in mils is laid off on the 
angle of site scale with the pointer and the desired range of 
graduation brought opposite the pointer by means of the 
elevating haulwheel. 

Operation of the Angle of Site and Elevating Mechan- 
ism. The angle of site mechanism is operated by turning 
handwheel, the movement of which is transmitted through the 
shafts and gears to the angle of site worm meshing with 
the rocker. Movement of the rocker is transmitted directly 
through the elevating worm, elevating arc, and spring cylinder 
to the gun, and through the rocker arms to the elevating 
mechanism, gun, cradle, and sights. The elevating mechan- 
ism moves only gun and cradle through movement of hand- 
wheel shafts, and the elevating worm inside the rocker, which 
meshes with the elevating arc. 

The angle of site scale is graduated in mils from 170 to 500. 
The range scale is graduated in meters. The zero setting of 
the gun is with on the range scale opposite 300 on the angle 
of site scale and the level bubble on the rocker arm, right, at 
the center of the tube. This allows the maximum depression 
of 7 degrees (about 130 mils) or the maximum elevation of 
11° of angle of site mechanism to be read on the angle of site 
scale against the zero of the range scale. 

The sight, model of 1916, which acts as a support for the 
panoramic or peep sight, is attached to the rocker arm, left. 

In direct fire, the axle of the bore is brought on the line of 
of site by operating the angle of site handwheel until the cross 
hairs of the sight are on the target and the range is laid off 
independently by bringing the desired range graduation op- 
posite 300 on the angle of site scale. Line of site may be set 



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TRAVERSING STOR 
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TRAVERSING RACK.- 
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TRAVERSING HANDWHEEL SHAFT. 

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— 375 HANDY OILER. 

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HALF BUSHINS,75*7Z5tRJP.GARRlAGE) 



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WASHER. 



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75 M M.GUN CARRIAGE. MODEL OF 1916. 



TRAVERSING MECHANISM. 



1 . 1 1 l 1 



75-MM. FIELD GUN, MODEL 1916. 133 

independent of the range, as there are two angle of site hand- 
wheels. 

Traversing Mechanism. The total traverse of the gun 
on the carriage is 800 mils. The traversing handwheel is 
located on the left side of the carriage and turns in a clock- 
wise direction for left traverse. 

The traversing handwheel shaft is mounted in the angle 
of site bracket, left, and the angle of site bracket cover, left. 
A bevel pinion on upper end of the shaft meshes with bevel 
gear on traversing shaft, which bears in angle of site bracket, 
cover, left and intermediate shaft bearing bolted to top car- 
riage. A bevel pinion at lower end of the intermediate shaft 
meshes with bevel gear on end of traversing-worm shaft, 
which is mounted in bearing in top carriage. Traversing 
worm meshes with traversing rack which is screwed to pintle 
bearing. Traversing stops are filister head screws between 
end teeth of traversing racks to limit movement of worm in 
rack. 

The movement of handwheel is transmitted through 
shafts and bevel gears to worm and rack. Rack is mounted 
in pintle bearing, which remains stationary, and top carriage 
moves about its bearing in center of pintle bearing and bronze- 
lined slides around the outside of pintle bearing. Traversing 
scale is screwed to pintle bearing above rack, and pointer is 
formed on traversing worm-shaft bearing. 

DISMOUNTING AND ASSEMBLING CARRIAGE. 

Note. — The first and most important precaution to be 
observed in assembling guns and carriages is that all parts 
must be clean. 

Where dismounting but not assembling operation is de- 
scribed, assembling is approximately the reverse of dismount- 
ing. 



134 FIELD ARTILLERY MATERIEL. 

I. To remove recoil cylinder. 

II. To disassemble recoil cylinder. 

III. To assemble recoil cylinder. 

IV. To dismount gun. 

V. To remove counter-recoil spring. 

VI. To remove breechblock. 

VII. To replace piston rod, gland pkg. 

VIII. To remove wheel. 

IX. To remove shields. 

X. To remove spring cylinder. 

XL To remove sight. 

XII. To remove rocker and rocker arms. 

XIII. To remove top carriage. 

XIV. To remove equalizing gear and pinions. 
XV. To remove brake mechanism. 

XVI. To remove trails. 

1. To Remove Recoil Cylinder- 

1. Remove valve turning gear cover (take out four 
3-8" bolts attaching it to the piston rod bracket). 

2. Remove valve turning gear, valve turning arm and 
connecting-rod as a unit by removing split pin, nut, and con- 
necting rod pin from trunnion cap, right. 

3. Remove piston rod (remove lash wire and two 3-16" 
split pins) slide piston rod gear forward and remove. 

4. Remove 1/4" locking screw from top of piston rod 
bracket. 

5. Remove 3-16" cylinder retainer screw and loosen 
cylinder retainer, but do not remove retainer. 

6. Remove brass spring-rod plugs from rear ends of 
both spring rods. 

7. Screw spring compressor eye into rear of left spring 
rod. Make loop in compressor and attach double sheave 
close to cradle. Attach single sheave to lunette by means of 
loose cord of sheave rope. 

8. Man pulling rope with from four to six men, retract 
gun not less than 10", and secure rope to lunette. 



75-MM. FIELD GUN, MODEL 1916. 135 

9. Remove cylinder retainer, slide cylinder forward 
until free of groove in gun and remove cylinder. Handle 
carefully. 

10. Allow gun to return to battery slowly by slacking off 
on pull rope. 

II. To Disassemble Recoil Cylinder. 

Note. — The interior parts of recoil cylinder are made with 
great accuracy to insure proper operation and must be handled 
with care to avoid injury. 

1. Remove recoil cylinder from carriage. (See I.) 
2^ Drain recoil cylinder by resting on blocks at front and 
rear, removing both filling plugs and drain plug, and tipping 
rear end up to allow all oil to flow out of drain-plug hole. 

3. Unscrew buffer-rod nut from rear cylinder head, draw 
out buffer rod until wrench can be applied on flats, and remove 
nut. Push rod back into cylinder. 

4. Remove lower splint pin from gland lock, swing 
gland lock back until free of notches in gland, and loosen 
gland with gland wrench. Unscrew front cylinder head with 
special wrench. Threads may be started by striking handle 
of wrench with soft hammer. Do not hold cylinder in a vise. 

5. Draw out piston rod slowly, supporting it at both 
ends as it leaves cylinder. Hold recoil valve in cylinder with 
ends of fingers. Keep receptacle under front of cylinder to 
catch surplus oil. 

6. Drain surplus oil from piston rod by holding vertically 
over receptacle with piston down and holding buffer rod in 
place. 

7. Rest piston rod on blocks, remove buffer-bushing 
locking screw, and unscrew buffer bushing, holding piston 
rod by wrench on flats at front end of rod. Have supporting 
blocks under both ends of rod so that rod will not be strained. 

8. Draw out buffer rod carefully. 



136 FIELD ARTILLERY MATERIEL. 

9. Draw out recoil valve with fingers. Remaining parts 
can now be easily disassembled. Buffer head is locked in place 
with bronze pin, which must be driven out before head can 
be unscrewed. 



III. To Assemble Recoil Cylinder. 

This operation is the reverse of II. Be sure that all 
gaskets and locking screws and pins are replaced and are in 
good condition. Be sure that all parts of mechanism are 
perfectly clean and dry, and that oil is clean. Oil must be 
strained through double thickness of clean cloth and if clean 
oil is not available use new oil. Do not make piston-rod gland 
too tight. Tighten with hand and screw up with wrench one 
additional notch to lock gland. Fill recoil cylinder before 
replacing on carriage, as follows : 

(a) With drain plug in place and filling plugs out, pour 
hydroline oil into filling hole slowly to avoid the formation 
of air bubbles. 

(b) When oil is level in filling-plug openings, tilt cylinder 
slightly to allow escape of air and replenish oil. 

(c) Loosen filling plug in front end of piston rod enough 
to allow oil to drip, and tighten plug. 

(d) Replace rear filling plug, raise front of cylinder abou t 
6 inches, and tap cylinder lightly with wood block or lead 
hammer to remove air. Level cylinder, fill, and replace front 
filling plug. Be sure that all gaskets are in place and properly 
centered. 

Note. — After recoil mechanism has been disassembled and 
replaced on carriage gun should be retracted 46 inches and 
eased back into battery slowly to be sure that it is properly 
reassembled. 



75-MM. FIELD GUN, MODEL 1916. 137 

IV. To Dismount Gun. 

1. Remove recoil cylinder (see I) and breechblock (see 
VI). 

2. Raise and block up trails in horizontal position, 
elevate gun until axis of bore is parallel with trails, and attach 
retracting mechanism (see 1-7) to left spring rod, retract gun 
about 6 inches, remove 3-16-inch split pin in left spring-rod 
key, and drive out key with bronze drift. Ease gun into 
battery slowly and permit further forward movement of spring 
rod until rope is slack and front end of spring-rod rests against 
spring cylinder cover. 

'3. Transfer retracting apparatus to right spring-rod, 
retract gun about 34 inch, remove split pin and spring-rod 
key, ease gun into battery until spring-rod rests against 
spring-cylinder cover, and detach retracting mechanism. 

Note. — In this position full pressure of springs is against 
cylinder cover and gun is free to slide in ways. Men should 
be kept from in front of spring-cylinder and care must be 
exercised to prevent tipping of cradle to the rear, which may 
cause gun to slide off. 

4. Bring gun to maximum depression. 

5. Lower trails to ground, spread trails against wheels, 
set brake, and bring gun to zero elevation. 

6. Requires seven men and four pick handles or imple- 
ments of almost the same length and strength. Slide gun 
about 36 inches to the rear by hand, place one pick handle in 
bore of gun at breech with one man, one pick handle with a 
man on each side under gun slides at front of cradle, and four 
men with two pick handles under gun as gun is drawn out. 

7. Push gun out of ways, supported by men, and re- 
move. 

Note. — In using pick handles do not place them under 
dust guards at gun lugs. Care must be taken to keep gun 



138 FIELD ARTILLERY MATERIEL. 

properly supported at same level as cradle guides at all points 
until free of guides. 

In remounting gun on cradle be sure that ways are well 
oiled and ways and slides thoroughly clean. Mounting gun 
is the reverse of IV. 

V. To Remove Counter-recoil Springs. 

1. Close and latch trails. (Open spring-cylinder cover.) 

2. Set brake and drive one spade (to secure carriage). 

3. Remove breechblock (see VI.) 

4. Attach spring-compressor to right spring rod (see 
1-7). 

5. Secure single block of retracting apparatus to fixed 
point, such as "dead man," driven spade, or tree. The hold- 
ing power of this fixed point must be at least equivalent to a 
driven spade and attaching point of rope should not be higher 
than center of spring rod. 

Note. — Sufficient slack of rope must be allowed to permit 
spring compressor to travel full length of spring cylinder and 
be detached from spring rod at front end. 

6. Retract gun about 6 inches, remove split pin in spring- 
rod key and drive out spring-rod key with bronze drift. 

7. Release retracting mechanism gradually until spring 
compressor rope is slack, draw spring rod out of front end of 
spring cylinder, and detach spring compressor. 

8. Attach retracting mechanism to spring rod, right. 

9. Retract spring rod about J^ inch, remove split pin, 
and drive out spring-rod key. 

10. Release retracting mechanism gradually until spring 
compressor rope is slack, draw spring rod out of front end of 
spring-cylinder and detach spring compressor. 

Note. — Assembly of counter-recoil springs is reverse of 
removal. The following precautions must be observed in 
assembling: 



75-MM. FIELD GUN, MODEL 1916. 139 

(a) If tension-spring compressor brings spring rod up 
solid against spring cylinder bushing in rear of spring cylinder, 
ease off rope slightly and pry up rod with bronze drift until 
it will enter the bushing. 

(b) Before key slot enters gun lug see that key ways in 
spring-rods and keyways in gun lugs are in line. If not, turn 
spring-rod by means of drift until keyways are in line. 

VI. To Remove Breechblock. 

1. Remove operating-shaft detent, slide operating handle 
to the right as far as the chain will permit, remove 1-16 inch 
split pin from studlink pin. 

2. Remove chain, piston rod, spring piston, piston-rod 
nut, and locknut as a unit by drawing out of closing-spring 
case. 

3. Remove closing spring from case. 

Note. — For complete instructions regarding disassembly 
of the breech mechanism see page 19. 

4. Remove trigger-shaft detent split pin and trigger- 
shaft detent by drawing it out of the breechblock to the right. 

5. Remove trigger shaft by prying gently straight down 
with screw driver or similar tool. Keep breechblock supported 
for all succeeding operations. 

6. Remove operating handle by sliding to the right and 
off operating shaft. 

7. Remove operating shaft by sliding to the left. 

8. Raise breechblock as far as possible (about 3-8 inch), 
move bottom part of operating arm to the rear, and remove 
operating arm. 

9. Remove breechblock by sliding down free of breech 
ring. 

10. Remove extractors by sliding toward center line of 
gun. 



140 FIELD ARTILLERY MATERIEL. 

VII. To Replace Piston Rod Gland Packing. 

(Packing, 4 rings, 5-16-inch square Garlock hydraulic 
packing.) 

(Gun in battery or cylinder removed.) 

1. Remove lower split pin from gland lock, swing gland 
lock up out of notch in gland. 

2. Unscrew gland with special wrench and slide forward 
on rod. 

3. Remove packing with bent wire. 

4. Insert five rings of new packing, one ring at a time, 
and push each ring home with packing tool of copper or hard- 
wood to fit into gland recess. Break joints in rings and tap 
packing tool lightly with hammer to drive each ring of pack- 
ing home. 

5. Screw up gland by hand and not more than three 
additional notches with wrench so that gland lock will catch 
and replace split pin. 

Note. — For the first few rounds after inserting new pack- 
ing there will be some leakage at gland and occasional tighten- 
ing will be necessary. Gland should not be screwed up tight 
with a wrench, as it can be made sufficiently tight by hand to 
prevent leakage if properly packed. 

VIII. To Remove Wheel. 

1. Raise and support carriage under equalizing gear 
near each. end (about 12" each side of center.) 

2. Disengage hubcap latch; unscrew and remove hub- 
cap. 

3. Disengage wheel fastening plunger and remove wheel 
fastening. 

4. Remove wheel. 



75-MM. FIELD GUN, MODEL 1916. 141 

IX. To Remove Shields. 

A. Top shield. — 1. Remove four §" pins, two §" 
locking pins, and lift off shield. 

B. Apron. — 1. Remove four §" hinge pins and remove 
apron. 

C. Cradle Shield. — 1. Remove two 3/32" split pins, 
nuts and bolts. On carriages number 625 to number 678 
inclusive, remove two cradle shield extensions. 

D. Main Shield, left. — 1. Remove six Y" bolts from 
shield bracket outer left. 2. Remove three \" bolts from 
shield socket, inner left. 3. Lift off shield. 

Main Shield, right — 1. Remove right wheel (see VII). 
2. Remove Y" pin from brake band end, remove adjusting 
not and force (by hand) brake band out of position, to clear 
main shield, right. 3. Remove four Y" bolts from shield 
bracket, outer right, and two Yi' bolts from brake lever 
bracket. Remove two 2/16" bolts from tool and remove tool 
carrier. Remove three \" bolts from shield bracket, inner 
right. 4. Lift out shield. 



X. To Remove Spring Cylinder. 

1. Remove recoil cylinder (I), gun (IV), counter recoil 
springs (V), sight (XI) and shields (IX). 

2. Remove trunnion caps (right and left) by raking 
out four split pins, loosening swing bolt nuts, and withdrawing 
Y" trunnion cap pins. 

3. Remove rocker stops (right and left) by taking out 
four split pins and f " bolts. 

4. Unlatch and spread trails. 

Note. — Seven men and four pick handles (or similar 
implements) are required for succeeding operations. 

5. Post two men with one pick handle at rear, two men 



142 FIELD ARTILLERY MATERIEL. 

with one pick handle immediately in front of elevating arc, 
and two men with one pick handle at front end of spring cylin- 
der. 

6. Raise cradle slowly, slightly to the rear until rocker 
clears top carriage. Carry to the rear sufficiently to rest mid- 
dle pick handle in trunnions and transfer two men with handle 
to rear of carriage. Continue to the rear sufficiently to rest 
front pick handle in trunnions, transfer men to rear, and re- 
move spring cylinder. 

XI. To Remove Sight. 

1. Remove three §" bolts from rocker arm, left. 

2. Remove one f " pin from sight lever in left trunnion. 

3. Remove sight and sight link. 

XII. To Remove Rocker and Rocker Arms. 

1. Remove spring cylinder (see X). 

2. Remove two 3/32" split pins, with f " nuts and bolts, 
two f " cap screws with lock washers, four \" screws, driving 
out four 0.247" by 0.34" by 0.872" keys from rocker arms, 
right and left. 

3. Remove rocker arm, left, by sliding up and out of 
rocker. 

4. Remove cross-shaft bearing cover by taking out 
three 3/32" split pins and removing three 3/16" nuts. 

5. Drive out \" pin from intermediate shaft t pinion, 
remove two \" split pins, two y%' nuts, one \" split pin, 
and one J^" cap screw from rocker-arm cap and remove 
rocker-arm cap. 

6. Lift out elevating handwheel and handwheel shaft as 
a unit. 

7. Draw intermediate shaft up and out of rocker-arm 
brace, draw rocker down from trunnions (keeping in line with 



75 MM. FIELD GUN, MODEL 1916. 143 

rocker-arm bearings) and remove. Swing rocker arm, right, 
up and around trunnions until free of range-scale bracket 
and remove. 

XIII. To Remove Top Carriage. 

1. Remove spring cylinder (see X) rocker and rocker 
arms (see XII). 

2. Remove angle of site bracket, left, by removing 
three split pins and nuts from § " bolts in angle of site bracket 
cover, left, taking off cover, removing nut and split pin from 
traversing handwheel shaft, removing handwheel and draw- 
ing .shaft out to the left. 

3. Remove two split pins and J^" nuts from cross shaft 
pinion case (left) bolts, extract bolts, and remove case. 

4. Remove cross shaft pinion case, right, as in XIII-3. 

5. Remove split pins and two nuts from cross shafts, 
right and left. 

6. Remove split pins and nuts from four Y^' studs 
securing angle of site bracket, left, and remove bracket with 
attached parts as a unit. 

7. Remove angle of site bracket, right, as in XI 1-5. 

8. Draw out cross shafts, right and left, and remove cross 
shaft pinions, right and left. 

9. Traverse top carriage to the right (by turning inter- 
mediate shaft gear by hand) sufficiently to allow traversing 
stop, rear to be removed. Extract split pin, remove nut, and 
take off traversing stop, rear. 

10. Traverse top carriage to the left until traversing 
worm is disengaged from rack, remove split pins and nuts from 
four studs securing traversing worm shaft bearing to top car- 
riage, and remove bearing and attached parts as a unit. 

11. Lift out traversing worm with attached parts as a 
unit. 



144 FIELD ARTILLERY MATERIEL. 

12. Turn top carriage to the right 90 degrees from zero 
azimuth, remove three screws that attach traversing rack to 
pintle bearing and remove traversing rack. 

13. Turn top carriage to the right 90 degrees (180 
degrees from zero azimuth), remove four screws that attach 
dust guard to pintle bearing and remove dust guard. 

14. Remove two screws that secure clip to pintle bearing 
and take off clip. 

15. Raise top carriage from pintle bearing. 

XIV. To Remove Equalizing Gear and Pinions. 

1. Remove top carriage (see XIII), wheels (see VIII), 
brake mechanism (see XV) and trails (see XVI). 

2. Turn pintle bearing bottom side up, remove 29 
screws which attach washers and binders and remove equal- 
izing-gear cover. 

3. Remove split pins and nuts from both locking ring- 
clamp bolts, unscrew and remove rings (one right, one left). 

4. Slide equalizing pinion off axle arms. 

5. Remove split pins from right equalizing-gear bolts, 
hold nuts tight, unscrew and remove bolt, remove nut and 
washer, remove left equalizing-gear bolt, nut, and washer in 
the same manner. 

6. Remove locking screw and equalizing-gear support 
(using special wrench). Lift up and remove equalizing gear. 

XV. To Remove Brake Mechanism. 

1. Remove wheels (see VIII). 

2. Remove brake bands, right and left, by extracting 
four split pins and removing four brake pins from ends of 
brake shaft. 



75-MM. FIELD GUN, MODEL 1916. 145 

3. Remove one split pin from each type "A" pin secur- 
ing brake lever, foot to brake lever bracket and to sleeve 
extension. Remove type "A" pins and brake lever. 

4. Extract two split pins from brake lever sleeve near 
center of carriage, draw out and remove brake shaft, left. 

5. Remove shield bracket, outer right, brake shaft, 
right and brake lever sleeve with all permanent parts attached, 
by removing main shield (see IX, D and E), removing split 
pin and nut from brakehanger bolt, taking out bolt, and 
sliding parts off axle arm. 

6. Remove shield bracket, outer left, by removing split- 
pin, nut, and brake hanger bolt and sliding brake hanger with 
permanent parts attached, off axle arm. 

XVI. To Remove Trails. 

1. Support carriage at front of pintle bearing. 

2. Remove two split pins and nuts from connection 
bolts, drive out bolts with copper drift, slide trails to the rear 
and remove. 

GENERAL INSTRUCTIONS. 

Filling Recoil Cylinder (Cylinder Mounted on Carriage.) 

If the recoil cylinder is not completely filled, loss of stabil- 
ity will occur and there is danger of serious damage to material. 
Before firing, a commissioned officer should always verify the 
filling of cylinder by removing one filling plug (with gun level) 
in which case oil should be visible above recoil valve. 

To fill recoil cylinder when assembled to carriage, elevate 
the gun about five degrees, remove both filling plugs and pour 
Hydroline oil in slowly with funnel until oil appears at rear 
filling plug hole. Level gun and again fill until oil appears at 
both filling holes. Shake carriage gently and continue to re- 
fill slowly until air ceases to come out of cylinder. Replace 

T. B.— 10 



146 FIELD ARTILLERY MATERIEL. 

rear plug, elevate gun about five degrees, remove valve turn- 
gear cover, and loosen plug in end of piston rod sufficiently 
to allow oil to drip out. As soon as oil starts to drip, tighten 
plug; be sure that gasket is centered. Replace rear filling 
plug, rock carriage to permit air to escape from filling hole 
anp 1 fill with oil. Replace plug, level gun, and perform same 
operation with rear filling hole. When air is all out of cylin- 
der, tighten both plugs and elevate to five degrees, allow to 
stand for about five minutes, then remove front plug and again 
refill. Loosen drain plug and drain out about }/i~gi\\ of oil 
into receptacle. Do not allow oil to run down into gun slides. 

About four quarts of Hydroline oil is required to fill re- 
coil cylinder. Oil must be clean and free from dirt and should 
be strained through clean linen or muslin cloth before using. 

In emergencies glycerin and water, or any buffer or engine 
oils may be used in recoil cylinders, but should be replaced by 
Hydroline as soon as possible. Where the above liquids are 
used, all interior parts of recoil mechanism must be emptied, 
disassembled, thoroughly cleaned and dried before refilling. 



75-MM. FIELD GUN, MODEL 1917 (BRITISH). 147 



CHAPTER VIII 
75-MM FIELD GUN MODEL 1917 (BRITISH). 

Weights and Dimensions. 

Weight 995 lbs. 

Caliber 2.95 in. 

Total length 88.21 in. 

Length of bore 83.915 in. 

Length of rifled portion 72.72 in. 

Rifling 24 grooves, right hand twist, zero turns at the origin 

to 1 turn in 75 in (25.4 calibers) at 9.72 in. from the 

muzzle thence uniform. 

The Carriage. 

Weight of carriage, complete 1950 lbs. 

Weight of gun and carriage complete 2945 lbs. 

Weight at end of trail carriage limbered 96 lbs. 

Diameter of wheels 56 in. 

Width of track 60 in. 

Length of recoil 49 in. 

Maximum angle of elevation 16 degrees 

Maximum angle of depression 5 degrees 

Maximum amount of traverse of gun on the carriage . . 142 mils 

DESCRIPTION. 

The gun is a combination of a built up and a wire wrapped 
gun. It consists of a tube, a series of layers of steel wire, 
jacket and breech ring. The tube extends from the rear end 
of the chamber to the muzzle. Over the rear portion of the 
tube are wound 15 layers of 0.04 by 0.25" steel wire. The 
jacket is fitted over the wire and the tube, and is secured 



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150 FIELD ARTILLERY MATERIEL. 

longitudinally by corresponding shoulders and the breech 
ring, which is screwed over the jacket at the rear, and secured 
by a set screw. The breech ring is prepared for the reception 
of the breech mechanism, and is provided on the upper side 
with a lug for the attachment of the hydraulic buffer. 

The breechblock is of the swinging type, interrupted screw 
with two threaded and two slotted sectors instead of the four 
we are familiar with in the 3". The firing mechanism is of 
the continuous pull type. 

The ammunition used is similar to that used with the 
American and French types of 75s. 

The Principal Parts of the Carriage are: 

Trail Elevating gear Shield 

Top Carriage Range gear Axle and wheels 

Cradle Traversing gear Sights 

Recoil cylinder Firing Mechanism Gravity tank 

Springs Brakes 

The trail is tubular. The top carriage houses bearings 
to receive the cradle trunnions and in travel it is locked to the 
trail. The bronze cradle pivots on the top carriage. The 
cradle trunnions support the sight. 

The recoil system is of the hydraulic-spring type. The 
recoil cylinder is surrounded by the counter-recoil springs 
which in turn are enclosed by a steel case — all of which is 
screwed on top of the cradle above the gun. The system 
operates in the same manner as the 3" materiel with the ex- 
ception that it possesses the additional feature of a gravity 
tank which replaces oil lost during firing. 

The elevating mechanism is of the doubled-ended screw 
type with the independent angle of site. The gears are so 
arranged that the elevation for range can be made without 
disturbing the laying for difference in elevation of the gun 
and the target, that is, the line of sight. The handwheel on 



Slide Protecto. 



Upper /%»t Cuned Protector - 
fhnoramic Sight Fori Shutter 

Foresight ff older 

Dust Cap 
— DrajkVasher 



-CTur\ 

- Piston Rod Nut 

- Cylinder Cap 
—Foresight 

- Brett f/andle 
—Mam Shield 

UpperSfiield 




Slevattny Handnheel(Upp;rr- 

Rocktng Bar 

Tra.ers in? tfand wheel 

Panoramic Sight 

oh.oulder Guard 



— Eccentric Link 

- Sight Bracket 

-Sight Lerel 

-Arc Connecting Bracket 

- Range Cejr Arc Cutde 

-Connecting Rod (Firing Lererl 

-Eccentric Link Connecting Rod) 

-Tensile Stay 

-Brake Lever 



■Seal Clip 

-Range Drum 

"tinier 
-fieri! mg Handwheel 
-Cradle Body 
- Inner Nut 
-Breech 

-Bottom Tube 
■TopTube 



L odttnq Band 

Seat- 



Actuating Scre*f3roke) • 
Actuating Screw fori -■ — 
Braie Shoe 







— Trad Spate 
-7rorers,ny- Ltrer 
Lifting Handle 
Pawl Stud 
I TFail Eye 

Trarersmq Lett? 



Securing Clip 



75 mm. 



Gun Carriage, Model sJ IS/7. British) 
Plan 



£»**& 



75-MM. FIELD GUN, MODEL 1917 (BRITISH). 153 

the right is for range to the target while the handwheel on 
the left is for the angle of site. 

The traversing mechanism is of the pintle type, consisting 
of a crosshead, link nut, and an actuating screw with a hand- 
wheel. It permits of a 72 mil. traverse either side of the center. 
A scale strip and a pointer indicate the angle of traverse. 

The firing mechanism like that of the American 75 is 
located on the left side of the gun instead of the right side as on 
the 3" and the French 75. The gun can be fired when it is 
within 2 inches of the "in battery" position, which increases 
the possible speed of firing. 



154 FIELD ARTILLERY MATERIEL. 



CHAPTER IX 
THE 4.7" RIFLE, MODEL 1906. 

GUN. 

Weights and Dimensions. 

Weight 2,688 lb. 

Caliber 4.7 in. 

Total length 134.92 in. 

Length of bore 129.42 in. 

Length of rifling 111.9 in. 

Number of grooves 42 

Twist Right hand. 

Weight of proj. based fuse 60 lb. 

Weight of proj. point fuse 45 lb. 

Weight of powder charge 95 oz. 

Muzzle velocity, 60 lb. proj 1,700 ft. per second 

Muzzle velocity, 45 lb. proj 2,050 ft. per second 

Maximum range 11,000 meters 

THE CARRIAGE. 

Weight of carriage complete 5,320 pounds 

Weight of carriage and gun complete 8,068 pounds 

Maximum elevation 15 degrees 

Maximum depression 5 degrees 

Maximum traverse 140 mils. 

The gun is built up and consists of a tube, jacket, locking 
hoop and clip. The jacket covers the rear half of the tube 
and projects beyond the tube at the rear to form the breech 
recess. The jacket also has a recoil lug on the under side for 
connecting the recoil cylinder. The clip is a short hoop near 



156 FIELD ARTILLERY MATERIEL. 

the muzzle and has guides formed on it to guide the gun in 
the cradle on recoil. The jacket also has guides formed on 
it. The length of the gun is approximately 11 feet. 

The breechblock is of the interrupted screw type having 
four threaded and four plain sectors. It is operated by a 
handle which swings from left to right turning and withdraw- 
ing the breech with one motion. An extractor is fitted for 
throwing out the shell case when the breech is opened after 
firing. 

The firing mechanism is of the type known as a contin- 
uous pull mechanism, that is, the mechanism is cocked and 
fired by the pull on the lanyard or by downward pressure o n 
the firing handle located at the right side of the breech. 

The recoil system is of the hydro-spring type. 

The two parallel steel tubes (the spring cylinders) are 
fitted into a frame surmounted by heavy steel rails which form 
the gun slides thus forming the cradle. The recoil cylinder 
is fitted between these two. 

The recoil and counterrecoil piston rods are attached to 
the gun lug and recoil with the gun, while the spring cylinders 
and recoil cylinder remain stationary. 

The recoil is constant, being 70 inches for all elevations. 
The recoil cylinder uses hydroline oil as the buffer medium. 
Throttling is obtained by three throttling bars running length- 
wise of the cylinder which are of varying height to give a 
throttling effect with corresponding slots in the recoil piston. 
A counterrecoil buffer is fitted in the piston rod to take up the 
shock when the springs return the gun into battery. 

The trunnions on the cradle are mounted in bearings 
formed by a yoke which swivels in a pintle bearing provided 
at the front of the trail. 

Traverse is obtained by means of a handwheel and screw 
mounted on the left side of the trail which swings the yoke in 



THE 4.7" RIFLE, MODEL 1906. 157 

traverse carrying the gun with it. A traverse of 70 mils on 
each side of center is possible. 

The piece is elevated by a double screw type of mechan- 
ism. The upper end is attached to the cradle and so raises 
and lowers it. The screw is operated thru gearing by two 
handwheels one on each side of the trail from 5° elevation dep. 
to 15° elevation. 

The trail is of the solid type made up of flasks of channel 
section. It has housings for the axle and carries the pintle 
bearing in which the top carriage or yoke swings. A tool box 
is provided in the trail. A seat is provided on each side of the 
trail for the cannoneers. The lunette transom is fitted about 
27 inches from the rear of the trail and carries a bearing that 
fits the limber pintle. 

A trail prop is provided for supporting the trail when 
limbering. 

The spade can be released and folded up on the trail 
when traveling. 

A traveling lock is provided on the trail for locking the 
gun when traveling. The piston rod and spring rods must be 
disconnected before the gun can be drawn back far enough 
to lock. 

The wheels are 61 x 6 inch with rubber tires and band 
brakes. Some older vehicles have steel tires and are fitted 
with tire brakes. 

An armor plate shield is fitted to the carriage for the 
protection of the personnel. 

The instruments for sighting and laying the piece included 
a line sight, a rear sight, a front sight, a panoramic sight and 
a range quadrant. 

The line sight consists of a conical point as a front sight 
and a V notch as a rear sight. These are located on the Jacket 
of the gun, and are useful for giving a general direction to the 
gun. 



THE 4.7" RIFLE, MODEL 1906. 159 

The sighting is similar to the 3", 1902. 

The rear sight and front sight are used for direct aiming. 
The rear sight is a peep sight mounted on a range scale quad- 
rant by a bracket on right side of the cradle. The front sight 
is a pair of cross wires mounted in a ring attached by a bracket 
on the cradle about 3 ft. ahead of the rear sight. 

The range scale quadrant has a socket in which the 
Standard U. S. Panoramic sight may be mounted. 

For indirect fire the gunner on the left of the carriage 
lays for direction only. 

On the right side of the cradle is mounted the Range 
Quadrant which has in combination with it the Angle of Site 
Mechanism. For indirect fire the gunner on the right of the 
piece lays for range with this instrument. 

Fixed ammunition is used with this gun. Shrapnel and 
high explosive shell are used. The base fuzed steel shell and 
the shrapnel weigh 60 lbs. The point fuzed steel shell weighs 
45 lbs. Gas shell are also issued identical with the 45 lb. steel 
shell. 



160 FIELD ARTILLERY MATERIEL. 



CHAPTER X 

THE 155-MM FILLOUX GUN. 
WEIGHTS, DIMENSIONS, ETC. 

Weight of Gun including breech 

mechanism 8,795 lbs. 

Length 232.87 inches. 

Caliber 155-mm (6.1042 inches.) 

Muzzle velocity 2,380 ft. -sec. 

Rifling, one turn in 2.989. Caliber, 
right hand uniform. 

Weight of projectile 95 lbs. 

Maximum range 16,200 meters. 

Weight of maximum powder charge 2534 lbs. 

Weight of carriage 11,065 lbs. 

Weight of gun and carriage, com- 
plete 19,860 lbs. 

Diameter of wheels 1,160mm. 

Width of track 2,250 mm. 

Height of axis of gun 1,482 mm. 

Elevation to 35 degrees. 

Maximum traverse 60 degrees. 

Weight of limber complete 3,190 lbs. 

Weight of gun carriage and limber. 23,050 lbs. 

The distance from center line of 
carriage axle to center line of 

limber axle, approximately. . . 4,500 mm. 

The gun is of the built-up type and consists of the tube 
strengthened by the following jackets and hoops beginning at 
the breech end: The breech ring, the jacket, the hoop A, 



1 1 




162 FIELD ARTILLERY MATERIEL. 

the hoop B, the clip hoop, the clip hoop set on the hoop B 
and the muzzle bell. The length of the gun from the muzzle to 
the breech base is approximately 18j^ feet. 

A recoil lug on the underside of the breech ring pro- 
vides means of attaching the recoil and recuperator rods. 
Hinge lugs for the breech are also formed on the breech ring. 
Bronze clips to serve as guides in the cradle are screwed to the 
sides of the jackets. 

The breechblock is of the interrupted screw type, having 
four plain and four threaded sectors. The breech mechanism 
is of the plastic obturator type, having the forward mush- 
room-shaped head of the breechblock equipped with the as- 
bestos ring, known as the obturator pad. Upon firing, this 
ring is compressed and acts as a gas check to prevent the leak- 
age of powder gases back through the breech. It has suffi- 
cient resiliency to resume its original form after firing. The 
firing mechanism is of the French percussion primer type 
which is described under *T55-mm Schneider howitzer" 
and is interchangeable with the guns enumerated therein. 

The cradle is a steel forging pivoted by trunnions in the 
trunnion bearings of the top carriage. It is bored with three 
parallel cylinders for housing the recoil and recuperator mech- 
anism. On its upper side are slots for the gun slides and the 
eievating rack is bolted to the lower side. 

The recoil mechanism is of the hydro-pneumatic variable 
recoil type. The larger of the three cylindrical bores in the 
cradle block contains the recoil mechanism; the two smaller 
ones, the parts of the recuperator mechanism. 

The recoil mechanism consists of a piston and piston rod 
and a counter rod. The piston rod is connected to the breech 
lug and, therefore, recoils with the gun. Grooves of variable 
depth are milled along the length of the counter rod, controlling 
the flow of oil through the ports of the piston during the recoil. 
This counter rod assembles within the bore of the piston rod. 








6^ 






38: 
si 



u- ** 8 



164 FIELD ARTILLERY MATERIEL. 

It does not move longitudinally, but rotates. The amount of 
this rotation changes the area of the orifices through which the 
oil can pass. Its rotation is accomplished as the gun is eleva- 
ted by means of an arm and gear sectors in such a manner as 
to shorten the recoii as the gun elevates. 

A replenisher or gravity tank is provided in connection 
with the recoil cylinder which assures the recoil cylinder being 
full at all times and also takes care of any expansion of the 
oil due to heating. Its capacity is about 17 quarts. 

The recuperator mechanism consists of two connected 
cylinders, one containing the piston and piston rod which are 
attached to the breech lug, while the other contains a mushroom 
valve and a diaphragm. The diaphragm separates the oil 
contained in the first cylinder and part of the second cylinder 
from the high pressure air which compels the return of the 
gun into battery after recoil. Normally a small amount of 
oil must be between the valve and diaphragm. Oleonapth 
is the liquid used in this recoil mechanism. The amount of 
oil in the recoil and recuperator mechanism is shown by an 
indicator so that it can always be seen whether or not they 
need filling. 

The top carriage is a large steel casting mounted on the 
bottom carriage on which it pivots to traverse the piece. 

The handwheels and mechanism for both elevating and 
traversing, are mounted on the top carriage. The tipping 
parts are carried on the trunnions of the top carriage. 

Belleville Springs carry the weight of the gun when 
traversing, but on firing the springs compress and the firing 
stresses are taken on the bearing surfaces between the top 
and bottom carriages. 

The bottom carriage is a large steel casting suspended 
from the axle (in traveling position) by a heavy multiple leaf 
spring. It supports the top carriage, houses the axle and pro- 
vides hinge connections for the trail. When firing the axle 



THE 155-MM. FILLOUX GUN. 165 

is unshackled from the left spring and the bottom carriage 
bears directly on the axle. 

Traversing is accomplished by turning the top carriage 
which pivots on the bottom carriage. This is done by means 
of a rack and train of gears which are operated by the hand- 
wheel on the left side of the carriage. A traverse of 60 degrees, 
30 degrees right and 30 degrees left, is possible. 

Elevating is accomplished by a rack on the cradle operated 
through gears by the handwheel located on the gear box at 
the left of the top carriage. Elevations from degrees to 35 
degrees can be obtained. 

The trail is of the split type and consists of steel plate 
beams of box section. Locks are pivoted at the forward end 
of the trails for securing them in the open position. When 
closed together they are clamped and attached to the limber. 
A traveling lock is provided on the trail for retaining the gun 
in retracted position. 

Two types of spade are pivoted, one for soft and one for 
hard ground. When traveling the spades are always removed 
from the trail. 

The wheels are of cast steel, each wheel having two solid 
rubber tires. 

Wheel shoes for traveling over soft ground are provided, 
which assemble over the rubber tires. They consist of twelve 
plates for each wheel which give a broad bearing surface under 
the wheel. The wheels are equipped with band brakes. 

The sighting equipment is exactly the same as that de- 
scribed with the 155-mm Schneider howitzer. 

The ammunition used is of the separate loading type. 
Either shrapnel or high explosive steel shell is used, as well 
as gas shells and other special ammunition. The projectile 
weighs 95 lbs. The propelling charge of smokeless powder 
is a sectionalized charge made up of two sections; a base 



166 FIELD ARTILLERY MATERIEL. 

charge and one smaller increment. The weight of the charge 
is 25 lbs. 

The fuzes commonly used are the 31 sec. combination 
fuse for use with shrapnel and combining time and percussion 
elements: the point detonating fuse Mark IV used with the 
steel high explosive shell and the mark III point detonating 
fuze used with gas shell. 



THE 155 HOWITZER, MODEL 1918. 167 



CHAPTER XI 

THE 155 HOWITZER, MODEL 1918 
THE HOWITZER. 

Weights and Dimensions. 

Material .,. .\ Alloy steel. 

Weight (including breech mech- 
anism) 1,248 kg.-2,745 lbs. 

Caliber 155-mm.-6.1 inch. 

Total length 2,332-mm.-91.8 inch. 

Length of bore 2,177-mm.-85.7 inch. 

Length of rifled portion of bore. . 737-mm.-68.4 inch. 

Rifling- 
Number of grooves 48. 

Width of grooves 7.145-mm.-0.2813 inch. 

Depth of grooves 1-mm. -0.03937 inch 

Width of lands 3-mm.-0.1181 inch. 

Twist, right hand, uniform, 
one turn in 25.586 cal. . . 

Powder chamber: 

Diameter 158.75-mm-6.25inch. 

Length 339.85-mm.-13.38 inch. 

Volume 6,965.75 cu. in. -425 cu. in. 

Obturation Pad 

Firing mechanism Percussion. 

General Description. 

The 155-mm howitzer, Model of 1918 (Schneider) is of 
the hydropneumatic long recoil type, which may be used for 
direct fire, but was specially designed for siege fire. On ac- 



168 FIELD ARTILLERY MATERIEL. 

count of its high trajectory it is able to direct shells on targets 
inaccessible to standard 6-inch howitzers of limited elevation. 

This howitzer has given satisfactory results in service and 
has proven to be more superior than guns of similar caliber. 
It has a muzzle velocity of 1,480 foot-seconds and attains a 
maximum range of 12,600 yards, the projectile weighing about 
95 pounds. 

A maximum rate of fire of four or five rounds per minute 
may be attained, but heating as well as difficulty of preparing 
and transporting the ammunition by the gun crew renders 
such rate impossible for more than a few minutes. How- 
ever, the normal rate of fire is two per minute and may be 
loaded at any degree of elevation. 

The howitzer is mounted on a sleigh and rigidly secured 
by means of a breech key and the holding down band. The 
sleigh contains the recoil and recuperator mechanisms which 
permits long recoil and insures stability at low elevations. 
When the gun is fired the sleigh recoils on bronze slides on the 
cradle, which is a U-shaped steel plate and rests in the trun- 
nion bearings of the trail. 

This howitzer may be elevated from degrees to 42 de- 
grees by means of the elevating mechanism. The traverse 
is 52.2 mils right and left, the carriage sliding on the axle 
and pivoting on the spade, which prevents the carriage recoil- 
ing when the gun is fired. The customary shield protects the 
gunners from flying shrapnel and fragments. 

In traveling position the howitzer is retracted and locked 
to the cradle, the cradle locked to the trail, the spade revolved 
and secured to the bottom of the trail. The lower end of 
trail rests on the carriage limber, which is used to carry the 
proportionate share of the load of the howitzer and carriage 
in traveling position. The limber is equipped with a con- 
necting pole for motor traction. The carriage and limber 



170 FIELD ARTILLERY MATERIEL. 

wheels are rubber tired and considered able to negotiate any 
roads suitable for field artillery. 

Howitzer Description. 

The howitzer, consists of a tube and jacket. The 
jacket is shrunk over, approximately, the rear half of the tube 
and screwed to it by a short thread near the rear end 
of the tube. The rear end of the tube is prepared for the 
reception of the breechblock. On the right of the jacket at 
its rear are two lugs which receive the hinge pintle of the 
operation lever. A flat seat with two transverse slots is 
machined on the top of the jacket at the rear end for receiving 
the counterweight. The counterweight is securely fastened 
to the jacket by six screws, and two lugs which engage the slots 
in the jacket. The bridle is fitted to the underside of the 
jacket near the rear end and held in place by four screws. 
The breech key passes through the bridle and holds the howit- 
zer in its seat on the sleigh. On the underside of the jacket 
just forward of the bridle seat are seven square threads which 
engage corresponding threads on the sleigh. A holding-down 
band which encircles the jacket at its forward end also secures 
the howitzer to the sleigh. 

On the top surface of the counterweight are two nickel 
silver leveling plates. 

Vertical and horizontal axis lines are cut on the breech 
and muzzle faces. A line showing the actual center of gravity 
with the breech mechanism in place is cut on the upper side 
of the jacket marked C. of G. The name and model of the 
howitzer are stamped on the left side of the jacket just below 
the counterweight. The name of the manufacturer, year of 
manufacture, serial number of the howitzer and the weight of 
the howitzer, including the breech mechanism, are stamped on 
the muzzle face. 



THE 155 HOWITZER, MODEL 1918. 173 

The breech mechanism is of the plastic obturator, inter- 
rupted screw type having four plain sectors and four threaded 
sectors. The block can be loaded with one-eighth of a turn. 
Two of the plain sectors are relieved to permit the breech- 
block to enter the breech recess. The breechlock is screwed 
into the block carrier and rides on the hub of the latter. 

The block carrier is hinged to the right side of the jacket 
by means of the pintle hinge of the operating lever. 

The pintle hinge is fitted at the lower end with an operat- 
ing lever collar and detent. The dead weight of the breech 
is carried by the block carrier hinge plate. 

The block is rotated by means of a rack which engages 
teeth cut in the upper surface of the block at its rear end. The 
rack is actuated by a lug on the under side of the operating 
lever which engages a slot in the rack. The rack is located 
in the inside face of the block carrier. When the breech is 
tightly closed this lock bears against the breech face of the 
howitzer and is forced back against the rack lock spring leaving 
the rack free to move. As the breech starts to open the rack 
lock is forced up by its spring and locks the rack, preventing 
further rotary motion of the breechblock. 

The operating lever is provided with an operating lever 
handle which is kept in its raised position by the operating 
lever handle spring. When the breech is closed and locked 
the lower portion of the operating lever handle engages the 
block carrier lever catch. When the breech is fully open the 
operating lever latch which extends through the operating 
lever, engages the operating lever catch and holds the breech 
in that position. 

The obturator spindle is of the mushroom head type. It 
passes through the center of the breechblock and is screwed 
into the front end of the firing mechanism housing, which fits 
into the hub of the block carrier. The obturator spindle is 
prevented from turning by the firing mechanism housing key 



THE 155 HOWITZER, MODEL 1918. 175 

spring. A vent for the passage of the primer flame is drilled 
through the center of the obturator spindle. The obturator 
spindle bushing is screwed into the front end of the obturator 
spindle and the obturator spindle plug into the rear end — 
the latter forming a chamber for the primer. 

The obturator spindle spring bears against the firing 
mechanism housing and the breechblock, keeping the head of 
the obturator spindle tightly against the gas check pad. The 
gas check pad or plastic obturator is composed of a mixture 
of one part asbestos and three parts nonfluid oil, contained 
in a canvas covering. The pad is protected by the front, 
rear and small split rings. A steel filling-in disk is placed 
between the gas check pad and the breechblock. 

The firing mechanism housing is provided with a firing 
mechanism safety plunger which is forced by the firing mech- 
anism safety plunger spring against the inside circumference 
of a circular boss on the face of the breechblock. When 
the breechblock is rotated to its locked position, the plunger 
slips into a notch in the boss and permits the entrance 
of the firing mechanism block. When the breech is unlocked 
the lower end of the firing mechanism safety plunger extends 
into the firing mechanism housing and obstructs the entrance 
of the firing mechanism block. This safety device makes it 
impossible to unlock the breech while the firing mechanism 
block is in place or to insert the firing mechanism block while 
the breech is unlocked. 

The firing mechanism block is provided with a handle, 
and screws into the firing mechanism housing. The primer 
seat plug is screwed into the front end of the firing mechanism 
block and is provided with a notch into which the primer is 
inserted. The firing pin guide is located just back of the pri- 
mer seat plug and forms a guide for the firing pin as well as 
a bearing for the firing pin spring. The firing pin housing is 
screwed into the rear end of the firing mechanism block and 



176 FIELD ARTILLERY MATERIEL. 

held in place by the firing pin housing holding screw. The 
firing pin passes through the firing pin housing and the 
firing pin guide and is forced to the rear by the firing pin spring. 
The firing mechanism block is provided with a flange at its 
outer edge in which a slot is cut to receive a projection on the 
front of the percussion hammer. This prevents the hammer 
from striking the firing pin when the firing mechanism block 
is not screwed home. The firing mechanism block latch is 
located on the outer face of the block carrier and prevents the 
firing mechanism block from being unscrewed accidentally. 

The firing mechanism block is interchangeable with the 
firing mechanism blocks used on the following cannon: 

155-mm. gun, model of 1918 (Filloux). 

8-inch howitzer, model of 1917 (Vickers Mark VI and 

vin y 2 ). 

240-mm. howitzer, model of 1918 (Schneider). 

The percussion hammer is carried by the percussion ham- 
mer operating shaft which is journaled in the percussion ham- 
mer operating shaft housing. This housing is secured to the 
breech face by means of a dove tail projection which fits into 
a slot, cut across the entire breech face just below the breech 
opening. The percussion hammer operating shaft is fitted 
with a lever at its right end which receives the blow of the 
firing mechanism striker when the lanyard is pulled. The 
percussion hammer shaft plunger and spring are located in the 
percussion hammer operating shaft housing to the left of the 
hammer. When the breech is open the plunger is forced up 
by its spring, thereby causing a projection on the plunger to 
engage in a recess in the operating shaft, locking the shaft 
so that the hammer cannot be operated. When the breech 
is closed the underside of the block carrier strikes on the 
beveled head of the shaft plunger, forcing it down and thus 
unlocking the mechanism. 



THE 155 HOWITZER, MODEL 1918. 177 

The percussion hammer lock bolt is screwed to the face 
of the carrier to the left of the percussion hammer. Its func- 
tion is to lock the hammer in the traveling position when the 
howitzer is not in use. 

Operation of the Breech Mechanism. When the breech 
is closed and locked, the threaded portions of the breechblock 
mesh with the threads in the breech recess. The operating 
lever is held by the lower end of the operating lever handle 
which engages the block carrier lever catch, thus preventing 
any rotary motion of the breechblock at the instant of firing. 
The firing pin receives the blow of the percussion hammer and 
fires the primer. The flame passes through the vent in the 
obturator spindle, igniting the propelling charge. The gas 
pressure in the bore forces the mushroom head of the obtura- 
tor spindle hard against the gas check pad causing the latter 
to expand and press against the walls of the chamber, forming 
a gas-tight joint. After the explosion the elasticity of the 
pad causes it to resume its former shape, allowing the obtura- 
tor to be withdrawn freely from its seat when the breech is 
unlocked. 

To Open the Breech. After the piece has been fired, and 
before unlocking the breech, press back the firing mechanism 
block safety latch, screw out the firing mechanism block and 
remove the used primer. The breech can not be unlocked 
with the firing mechanism block in place. An attempt to 
do so will result in jamming of the firing mechanism safety 
plunger. It is therefore important that the firing mechanism 
block should be removed before attempting to unlock the 
breech. 

Press down on the handle of the operating lever in order to 
disengage it from the block carrier lever catch. Move the 
lever toward the rear and then to the right. In the first part 
of this movement, the operating lever turns freely around the 



178 FIELD ARTILLERY MATERIEL. 

hinge pin and its lug operates the rack which turns the breech- 
block. The threaded parts of the breechblock are thus 
disengaged from the threads in the breech recess. As the 
rack reaches the limit of its travel, the block carrier is swung 
on its hinge drawing the breechblock out of the breech recess. 
As the block carrier leaves the breech face of the howitzer 
the rack lock is forced by its spring into the recess in the rack 
preventing any further rotary motion of the breechblock in 
either direction. As the breech reaches its full open position 
the right end of the operating lever catch engages the operat- 
ing lever catch, locking the breech in open position. 

In loading, care should be taken to ram the projectile 
home and to enter the propelling charge in such a way that the 
igniter of the base charge will be in contact with the mush- 
room head of the obturator spindle when the breech isclosed. 

To Close the Breech. Press down on the operating lever 
handle to disengage the operating lever latch from the opera- 
ting lever catch and move the operating lever to the left and 
forward. As the block carrier comes in contact with the 
breech face of the howitzer, the rack lock is pushed back into 
its seat, freeing the rack. Further movement of the operating 
lever forces the rack to the left, rotating the breechblock until 
its threaded portions mesh with the threads in the breech 
recess. At the end of the movement of the operating lever, 
the operating lever handle engages the block carrier lever 
catch and fastens the breech in locked position. 

Insert a new primer in the primer seat plug and replace 
the firing mechanism block. The firing mechanism block 
can not be entered until the breech is closed and locked. Any 
attempt to do so may cause damage to the firing mechanism 
safety plunger or some part of the firing mechanism. 



THE 155 HOWITZER MODEL 1918. 179 



THE CARRIAGE. 

For the purpose of description, the carriage is considered 
as composed of the following groups: Sleigh (including recoil 
mechanism), cradle, trail, traveling lock, elevating mechanism, 
traversing mechanism, wheels, road brake, and shield. 

The sleigh contains the recoil and counter-recoil mechan- 
ism and serves as a support for the howitzer, being secured to 
it by the breech key and the holding-down band. The recoil 
counter-recoil cylinders, and two air cylinders are bored in 
the sleigh and form the recoil mechanism. The ends of the 
recoil and counter-recoil cylinders are attached to the cradle 
and when the howitzer is fired the sleigh and howitzer recoil, 
sliding on the cradle sides. 

The holding down band is anchored on either side to the 
front band clips, which are secured to the sleigh. Grooves 
are cut underneath the two top edges of the sleigh, and are 
lined with bronze liners, known as sleigh slides. These liners 
slide on the cradle clips and guide the howitzer during recoil. 
Five longitudinal cylinders are bored in the sleigh, the two 
upper cylinders running about one-third the length of the 
sleigh, forming air tanks and are closed at the front end by 
the air tank heads. The left air tank head is provided with 
an opening in which the gage-cock body is assembled,. A 
pressure gage may be assembled through an adapter to this 
gage-cockf or ascertaining the pressure in the counter recGil 
system. The gage-cock is also provided with a pointer which 
registers the quantity of liquid in the system on a scale pro- 
vided on the air tank head. The two lower cylinders ex- 
tending the full length of the sleigh, form a housing for the 
recoil mechanism, the rignt cylinder being the counter-recoil 
cylinder and the left the recoil cylinder. The small equalizing 
cylinder in the center of the sleigh, extending only a short 




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THE 155 HOWITZER, MODEL 1918. 181 

distance, is closed at the front end with the filling valve, 
through which air or liquid is introduced into the system. 

The counter recoil cylinder is connected by a passage to 
the right air tank and also to the small equalizing cylinder, 
the latter being connected to the left air cylinder, thus main- 
taining equal pressure in both air cylinders and in the counter- 
recoil cylinder. The counter-recoil cylinder is closed at the 
rear end with the counter-recoil cylinder head and at the front 
end with the stuffing box, through which the counter-recoil 
rod and its piston moves. The recoil cylinder is closed at the 
rear end with the recoil cylinder head and at the front end with 
the recoil cylinder stuffing box, through which the recoil pis- 
ton rod operates. This rod is hollow and serves as a buffer 
chamber for the buffer rod, which is securely screwed to the 
recoil cylinder head at one end, the other end carrying the 
counter-recoil valve. The recoil and counter-recoil rods are 
fitted with the piston rod nuts on the front end which engage 
the piston rod lock plate. 

The cradle is a steel U-shaped plate reinforced by several 
transoms and supported by the trunnion bracket, elevating 
segment brackets, and in traveling position by the cradle band 
which engages the clips on which the howitzer recoils when in 
action. The sleigh traveling locks are mounted at the extreme 
ends of the cradle and used to lock the sleigh to cradle when 
the howitzer is in traveling position. 

The cradle is mounted on trunnions on the carriage, and 
by means of elevating segments geared with the elevating 
mechanism may be inclined at various firing angles. When 
carriage is traveling the rear end of the cradle rests on the 
cradle traveling lock, thereby relieving the elevating mechan- 
ism of the weight of the howitzer, sleigh and cradle. 

The left trunnion of the cradle is bored out to receive the 
sight and bracket. The shoulder guard is located on left 



182 FIELD ARTILLERY MATERIEL. 

side of the cradle just back of the trunnion bracket and pro- 
tects the gunner from the recoiling parts. The firing mech- 
anism is located on the right side of the cradle and provided 
with a safety device which prevents the piece from being 
fired when the piston rod nuts are not engaged by piston lock. 

The recoil indicator is located just back of the trunnion 
bracket on the right side of the cradle and consists of a 
steel spring which is adjusted by means of a nut so that the 
pointer bears against a scale engraved on the edge of the 
sleigh indicating the length of recoil. The front end of the 
cradle is covered by the cradle head and provided with an 
opening through which the pressure-gauge adapter may be 
assembled to the gauge-cock body. The lower half of the 
front end of the cradle is closed by the front transom, forming 
a guide for the piston-rod lock which is operated by means of 
a lever. When this lever is lowered the lock plate moves to the 
right, releasing the piston-rod nuts. When the lever is raised 
the lock moves to the left, locking the nuts in firing position. 
The locking device is protected by the cradle front cover which 
holds the lever in firing position when closed. The filling 
valve is accessible through the cradle bottom cover located on 
the bottom of the cradle to the rear of the front transom. The 
pump bracket is located on the left side of the cradle near the 
front. 

Recoil and Counter-Recoil Mechanisms. When the how- 
itzer is fired the recoil mechanism exercises its retarding in- 
fluence by means of a liquid which is obliged to pass through 
an orifice whose size diminishes as the movement proceeds, 
thus checking the recoiling mass. The recoiling movement 
of the gun actuates at the same time the counter-recoil mechan- 
ism, which acts on the counter-recoil liquid and forces it into 
two reservoirs, thus further compressing a gas therein con- 
tained. When the recoil movement is ended the expansion 
of gas forces the counter- recoil mechanism back "into battery," 



•mm 




3= CC 
C3 Uul 






(■xoyddv)'t>i?i- 






THE 155 HOWITZER, MODEL 1918. 185 

and the recoil cylinder again exercises its retarding influence 
to prevent a too rapid return and shock. The normal recoil 
is 51.375 inches (1.305 meters). 

When the piece is fired the howitzer and sleigh move to 
the rear, the recoil and counter-recoil rods, which are held by 
the piston-rod lock remaining stationary. The liquid in the 
counter-recoil cylinder is thus forced into the air cylinders, 
building up a pressure sufficient to return the howitzer to bat- 
tery. The liquid in the recoil cylinder is forced through the 
orifices in the recoil piston rod and then through the throttling 
ring. The tapered buffer rod, which is attached to the recoil 
cylinder head, moves through the throttling ring, gradually 
closing the orifice, thus keeping the pressure constant as the 
velocity of recoil is reduced. As the buffer rod moves to the 
rear the counter-recoil valve is opened, allowing the liquid 
to pass freely into the buffer chamber. As the gun returns 
to battery the buffer valve closes, forcing the liquid to pass 
through the small clearance around the valve, thus absorbing 
the energy of counter recoil. 

By means of the elevating mechanism the howitzer, 
sleigh and cradle are inclined at the various firing angles, 
varying from zero to 42 degrees, by rotation in the trunnions 
of the cradle. 

Two elevating segments attached to the cradle are actua- 
ted by the elevating pinion shaft operating in bearings inte- 
gral with the elevating worm wheel case secured to trail. To 
lower end of worm shaft is fitted a worm which engages a worm 
wheel and pinion shaft in the gear case. On upper end of 
worm shaft is attached the elevating hand wheel fitted with 
a handle and plunger enabling the operator to lock the how- 
itzer at any desired elevation. The motion of the handwheel 
is transmitted through the worm gear to the pinion shaft and 
thence to the elevating segments. 








£3 



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is 



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to 

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THE 155 HOWITZER, MODEL 1918. 187 

The handwheel is provided with a handle of a spring lock- 
ing type, downward pressure on which unlocks it from the 
handwheel latch plate, permitting the mechanism to be opera- 
ted. 

Traversing Mechanism. The traverse of the carriage is 
obtained by means of the traversing mechanism causing the 
carriage to slide on the axle, the trail pivoting on the spade. 
The movement is 3 degrees each side of center or a total of 
Id5 mils. 

At the center of the axle is rigidly attached a bronze 
traversing nut through which passes the traversing screw 
which may be operated from either side of the carriage by 
means of handwheels connected to the screw through bevel 
gears and shaft. The traversing screw operates in the traver- 
ing housing longitudinally and held in position by thrust 
bearings and thrust bearing adjusters at both ends of the 
screw. When either of the handwheels is operated the trav- 
ersing screw is rotated and moves to the right or left as the 
case may be, carrying the entire carriage which moves across 
the axle on traversing rollers. 

In order to reduce friction during the traversing opera- 
tion the carriage rests on the axle through Belleville springs 
and two concave faced traversing rollers mounted on roller 
shafts in the axle housing. When gun is fired the Belleville 
springs are compressed and the carriage rests on the axle 
through the bronze traversing roller boxes. 

On top of axle projecting to the left of carriage is riveted 
an azimuth scale graduated in mils so that the position of the 
carriage on the axle may easily be seen at any time. When 
in traveling position the carriage should be locked to the axles 
by the axle traveling lopk, thus relieving the traversing mech- 
anism from unnecessary stress. 

The axle traveling lock is a device employed to relieve 
the traversing mechanism from unnecessary stress when the 



THE 155 HOWITZER, MODEL 1918. 189 

carriage is in traveling position. When the carriage is pre- 
pared for traveling the traveling lock engages a series of square 
grooves cut in the center of the axle. The lock is operated 
by an eccentric on the end of the traveling lock shaft which 
is controlled by the lock lever fixed on outer end. The lock 
lever may be placed in two positions marked "to travel" and 
"to fire," by means of its handle which is provided with a spring 
plunger engaging the traveling lock catch. In order to prop- 
erly lock the carriage in traveling position it is necessary to 
traverse the carriage to the center position on the axle, thus 
permitting the locking device to engage the grooves cut in the 
center of the axle. 

The air pump is furnished for the purpose of charging 
and maintaining the necessary pressure in the counter recoil 
reservoirs. When in operation it is attached to a bracket on 
the carriage by means of a screw clamp and connected to the 
reservoir by the filling pipe. The pump will operate against 
a pressure of 400 to 600 pounds per square inch. 

The liquid pump is a single-acting-plunger used for charg- 
ing the counter-recoil system and for the purpose of replenish- 
ing losses of liquid from the cylinders. Power is applied 
through a hand lever connected by parallel links and a cross- 
beam at the lower end of the piston. The hand lever is de- 
tachable and also used in connection with the air pump. When 
in operation the pump is attached to a bracket on the carriage 
by means of a screw clamp. The filling pipe is employed to 
connect the liquid pump with the recuperator cylinder. 

The reservoir for compressed gas is a commercial seam- 
less cylinder with a capacity of 2,842 cubic inches and is 
charged with nitrogen gas at a working pressure of 2,000 
pounds per square inch (140 kilograms per square centimeter). 
The reservoir is provided with a needle valve and a connection 
for the pressure gage or filling pipe. This cylinder is used 




WS 53 



6>3 



I»l 



f»j ee 



192 FIELD ARTILLERY MATERIEL. 

for charging the counter-recoil system and may be carried 
on the artillery supply truck furnished with 155-mm organi- 
zations. 

The filling pipe is used to connect the counter-recoil reser- 
voirs with the air or liquid pump or with the compressed gas 
reservoir. 

Pressure Gage. The gage for the compressed gas reser- 
voir is calibrated from to 150 kilograms per square centi- 
meter. It is used to ascertain the pressure of gas in the reser- 
voir and must be attached before screwing on the filling pipe. 
The gage for the pressure-gage adapter is calibrated from to 
60 kilograms per square centimeter, is screwed into the side of 
the adapter and used to test the pressure in the counter-recoil 
system. 

The quadrant sight, model of 1918 (Schneider), is 

mounted on the left trunnion of the carriage, both in traveling 
and in action, and should not be removed by the battery 
mechanics. The principal features of the quadrant sight are : 
The cross-leveling mechanism, the elevating mechanism, and 
the angle of site mechanism. 

The cross-leveling mechanism principally consists of the 
leveling worm, leveling stop, antibacklash spring, leveling 
clamp, and cross levels. By means of the cross-leveling 
mechanism the quadrant sight is adjusted to proper align- 
ment with the bore of the howitzer. 

The bracket fits into the trunnion on the left side of the 
carriage and is provided with four tennons which engage 
slots in the face of the trunnions keeping the sight in proper 
alignment with the bore of the howitzer. The bracket is 
screwed in place by the bracket bolt; the front end of the body 
of the quadrant sight fits into the cylindrical parfof the bracket 
and is held in place longitudinally by four lugs. 



194 FIELD ARTILLERY MATERIEL. 

The body of the sight is rotated by the leveling worm en- 
gaging the worm segment cut on the under side of the body. 
The outer end of the worm is provided with a knurled hand 
wheel by means of which the levling mechanism is operated. 
The leveling stop, secured to bracket, engages slot in the body, 
thus limiting the angular motion of the body in either direc- 
tion. The rear end of the cylindrical part of the bracket is 
split and provided with a leveling clamp by means of which 
the body may be locked in position after it has been leveled. 

The cross level is located on the rear edge of the sight shank 
and serves the gunner in determining the level position of the 
instrument. The level vial is a glass tube, closed at both ends, 
and partially filled with a liquid consisting of 4 per cent alcohol 
and 60 per cent ether, a small bubble remaining in the tube. 
Graduations are etched on the circumference of the tube to 
indicate the central position of the bubble. The vial is held 
in a level-vial tube, the ends being wrapped in paper and set 
in plaster of pans. The knurled cross-level cover fits over 
the holder and, together with the level-vial tube, are held in 
place by the cross-level caps, which close the ends of the holder. 
When closed, the cover serves as a protection for the vial. 

The elevating mechanism consists principally of a sight 
shank, elevating worm wheel, antibacklash pinion, elevating 
worm, elevating worm eccentric, elevating scale drum, and 
scale drum housing. 

NOTES ON CARE OF THE 155 HOWITZER. 

The executive should be perfectly familiar with the 
working of the recoil and know when to put a gun out of action 
due to faulty recoil. The length of the recoil should be such 
that the end of the gun slides do not recoil over the end of the 
cradle rails. In counter-recoil, the sleigh should be per- 
ceptibly slowed down at a point about 10 centimeters from the 
front of the cradle, and from there on should ease gently into 



THE 155 HOWITZER, MODEL 1918. 195 

battery without a sound or shock. Strict watch should be kept 
to see that no excessive leakage takes place through the stuffing 
boxes, the valve in the gauge adapter, or the oil hole in the 
cylinder end nut. Slight leakage can hardly be helped, as one 
of the stuffing boxes is under more than four hundred pounds 
of pressure per square inch when the gun is at rest, and three 
or four times that amount when the gun is in full recoil. 
However, if a pool of liquid is found after the gun has been 
standing all night, it is time to report the matter and have the 
packings replaced. The gun must be dismounted, the stuffing- 
box repacked, and the dermatine inspected. The dermatine 
packing is a compound resembling rubber, but it has the qual- 
ity of resisting any chemical action that the liquid may set up 
in the recuperator. A worn dermatine packing may be re- 
placed by the simple expedient of turning it wrong side out 
and then using it again as before. This has actually been tried 
and found to give good results. Another temporary repair 
was effected by cutting a ring from a solid truck tire and using 
it in the place of the dermatine, until a packing of the latter 
could be obtained. 

The French obtain a very tight fit in their stuffing boxes 
by the peculiar design that allows the liquid pressure to actu- 
ate a strong spring which in turn expands the packing against 
the rod or cylinder wall. Leakage through the recuperator 
stuffing box will be noticed by the liquid coming out of the 
oil hole in the right-hand cylinder end nut. 

In dismounting French materiel, care must be used to 
replace the same nuts on the bolts from which they were taken. 
Threads are not standardized as to diameter; hence, trouble 
is likely to occur when remounting. 

To dismount the tube from the recoil mechanism, or 
sleigh as it is denoted, a suitably strong overhead beam is 
selected and the carriage run beneath it. Mount two one- 
ton duplex blocks on the beam over either end of the tube 



196 FIELD ARTILLERY MATERIEL. 

and thread the bore with a half-inch wire cable sling, in such 
a manner as to leave a bight at both muzzle and breech ends. 
Into these loops the hooks of the block catch. Gunny sacks 
form a suitable packing at the muzzle and breech to prevent 
the cable damaging these parts of the tube. Provide several 
blocks of two by four or four by four stuff, to block up the 
sleigh as it is moved to the rear — as we shall soon see that it 
does. Remove the locking hoop by knocking out the retaining 
bolts, and also remove the cradle bolts from their housing on 
the cradle. This will allow the sleigh to move to the rear of 
the cradle. Take a strain on the blocks and carefully move 
the sleigh back over the trail until the recoil-lug key (locking 
the recoil lug to the sleigh) clears the end of the cradle. Re- 
move the set screw from the bottom of the sleigh which locks 
the tapered key in place, and proceed to drive the key out with 
a sledge hammer and a block of wood. During this operation 
the rear of the sleigh must be blocked up on the trail in order 
to take the strain off the cradle rails. After the key is 
cleared, the tube may be raised by means of the two blocks, 
care being taken to make the lift vertical, otherwise the slots 
and grooves just in front of the breech will jam and be dam- 
aged. Remove the carriage and lower the tube onto blocks. 
The process of mounting is just the reverse of the above. 

The elevating and traversing mechanisms give little 
trouble, if all gear cases are kept packed in grease. It is 
extremely important that, in laying for elevation with this 
piece, the final turns of the handwheel should bring the gun 
into correct position by raising the breech and not by lowering 
it. In this way all blacklash is taken out of the gearing and 
the howitzer rests solidly for firing. The gunner may easily 
be taught to remember this by always having him bring the 
range bubble to the front of the glass and then slowly elevate 
the breech, bringing the bubble to him. 



THE 155 HOWITZER, MODEL 1918. 197 

The traversing mechanism moves the whole carriage, 
including gun, along the axle, about the spade as the center 
of rotation. The traversing screw moves the carriage by- 
being rotated through nut set solidly in the axle. The axle 
and nut are stationary and the screw moves laterally by means 
of the traversing handwheel. Hence, the carriage being at- 
tached to the, screw, must move when the screw moves. In- 
asmuch as the axle is straight, it must accommodate itself to 
the arc of the circle described about the spade as the centre. 
It does so by moving tangent to the arc, and consequently one 
end moves to the front and the other end moves to the rear, 
carrying the wheels with them. From this it will be seen that 
before attempting to traverse the piece, the brake must be 
''off." The movement of the wheels may be easily seen, if a 
pencil line be drawn across the tire just above the brake shoe 
and then the piece traversed. The line will be seen either to 
raise or lower according to whether the piece be traversed to 
the right or left. 

In filling the ' 'brake" or recoil cylinder, good results have 
been obtained by merely leveling the gun and filling the 
brake cylinder until full. Trying to pour out one hundred 
cubic centimeters of the liquid after the brake is full, as the 
French drill regulations lay down, is almost impossible; and 
no bad effects will be noticed provided the gun does not be- 
come excessively warm during the firing. If it should become 
warmed up sufficiently to affect the recoil, level the gun, un- 
screw filling plug to release the pressure, rescrew, and continue 
the fire. In using the manometer gauge, to measure the pres- 
sure and the height of the liquid in the recuperator, it will be 
found that the valve in gauge adapter will sometimes stick 
open to the extent of letting out all the air in the recuperator 
tanks. The only sure remedy for this is entirely to dismount 
the gun, remove the adapter, and replace its valve packing, 
which no doubt will be found to be worn and frayed, or else 



198 FIELD ARTILLERY MATERIEL. 

some foreign substance will be found to be lying between it 
and its seat. The gauges should be tested about once in three 
months by means of a standard steam gauge testing appara- 
tus, making the appropriate transformations if the tester be 
graduated to pounds per square inch as most steam testers 
are. It will be found that the maximum steam pressures 
used are rather lower than these gauges read, hence only the 
lower readings may ordinarily be tested. 

To set the pointer to the correct pressure reading, pull the 

pointer loose and apply a known pressure to the gauge. Set the 

pointer at the corresponding reading on the manometer and press 

it on tightly. In general, this is sufficient for practical work. 

After each firing the breechblock should be entirely dis- 
mounted and each part washed in caustic soda solution and 
then stippled with oil before reassembling. 

The wheels are made of smaller members than those that 
we are accustomed to see in our own materiel. It must be 
remembered, however, that the French designed their wheels 
for much better roads than ours; and, in comparison with 
our materiel throughout, this fact must be borne in mind. 
The wheels must be carefully watched, especially through the 
dry weather, for they tend to check and crack. Remedies 
are tire shrinking and soaking in water over night, followed 
by a thorough and careful application of linseed oil. Fast 
travel, as when the piece is coupled to a truck, must be avoided 
if the life of the carriage is to be assured. 

According to the French drill of the gun squads, in going 
into action, the piece is first unlimbered and the trail is then 
laid on the ground, and the cannoneers change posts to the 
extent of the gunner going to his position by his sight; while 
the remaining cannoneers lift the trail again and set the spade. 
This is slow and cumbersome work. Much better results may 
be obtained by setting the spade at the time that the piece 
is unlimbered, without moving the cannoneers from their posts. 



EXPLOSIVES, AMMUNITION AND FUSES. 199 



CHAPTER XII 

EXPLOSIVES, AMMUNITION AND FUSES. 

EXPLOSIVES. 

As a matter of practical interest, explosives may be divided 
into three classes, namely: 

(1) Progressive or propelling explosives called low ex- 
plosives. 

(2) Detonating or disruptive explosives, termed high 
explosives. 

(3) Detonators or exploders, known as fulminates. 

The first includes all classes of gun powders used in fire- 
arms of all kinds; the second, explosives used in shell, tor- 
pedoes, and for demolitions; the third, those explosives used 
to originate explosive reactions in the two first classes. Cor- 
responding names are given to the phenomena characteristic 
of each class of explosives, (1) explosions proper, of low order, 
progressive, or combustions, (2) detonations, of high order, 
(3) fulminations, this last possessing exceptional brusqueness. 

The explosion of low order is marked by more or less 
progression ; the time element is involved as a controlling fac- 
tor, the time required to complete the explosive reaction being 
large compared with that of the other forms of explosion. 

The second class of explosion is of a different nature. 
The explosive reaction is not limited or confined to the sur- 
faces exposed but appears to progress in all directions through- 
out the mass radially from the point of initial explosion. It 
has been determined experimentally that the velocity of propa- 
gation of the explosive wave throughout a mass of guncotton 
is from 17,000 to 21,000 feet per second. 



200 FIELD ARTILLERY MATERIEL. 

Fulmination is a class of explosion still more brusque 
than the last. The abruptness of their explosion and the con- 
sequent sharpness of the blow and the concentration of heat 
on the point of ignition constituting their efficiency as origina- 
tors of explosions of the first two classes. 

Methods of Exploding. Explosives may be exploded by 
three methods; in reality but two, by heat and by application 
of energy as by a blow. The heat may be applied directly 
by friction, by electricity and detonating cap, these two 
methods of applying the heat giving rise to the three practical 
methods above mentioned. As it is not practical to apply heat 
directly to the charge, small charges of special explosives are 
made up into primers and these are exploded in one of the ways 
above mentioned and so communicate the explosion to the 
main charge. Fulminate of mercury is one of the high ex- 
plosives fulfilling the requirements and it is readily exploded 
by any one of the methods mentioned. It is used in all de- 
tonating caps. Primers for cannon also contain an additional 
charge of black powder to increase the flame. For this pur- 
pose also igniting charges of black powder are attached to the 
smokeless powder charges for the larger calibers. 

Uses. The chief use of low or progressive explosives 
is as a propelling charge in guns and for blasting where it is 
desired to exert a pushing effect rather than a blow. High 
explosives are used when it is desired to exert a high pressure 
and shatter the container, as in a shell, mine, etc. This class 
is not satisfactory as a propelling charge for the reason that 
its rapidity of action is so great that the pressure exerted 
would burst the gun before the projectile could start. Low 
explosives are not satisfactory shell fillers for the reason that 
their action is so low that the shell would break at its weakest 
point before all the explosives had exploded and what re- 
mained would be wasted. With a high explosive, all or most 



EXPLOSIVES, AMMUNITION AND FUSES. 201 

of the charge explodes before the shell can break up. The 
greater the rapidity of action of an explosive the finer the 
fragmentation of the projectile. With too rapid action the 
pieces are too small; with too slow action they are too large. 
Experience teaches the proper rapidity of action to attain 
the fragmentation most efficient against animate and material 
targets. 

Propelling Charges. Up to the present time nitrocellulose 
powder has complied better with the requirements of a suit- 
able, smokeless powder than any other that has been proposed 
and is used in our service for propelling charges in guns. The 
danger of manufacture is also less than that of nitroglycerine 
powders. Moreover the latter, which was formerly used in 
our service and still is in the British and some others, causes 
too much erosion of the tubes due to the greater heat of ex- 
plosion. It has the advantage of requiring a smaller charge 
for the same muzzle velocity and therefore a smaller powder 
space and consequent lighter weight of gun. 

Shell Fillers. High explosives for shell fillers. Up to 
the present explosive U D," trinitrotoluol and picric acid are 
the principal high explosives which fulfill the requirements as 
shell fillers. Explosive "D" on account of its great insensitive- 
ness to shock is used in armor piercing projectiles and also in 
field gun and howitzer shell. It is detonated by a fuze. 
Trinitrotoluol is used in submarine mines and in general de- 
molition work as it is much easier to explode than explosive 
"D." 

Table of Explosives. The following table gives a good 
idea of the principal explosives in use in our service and the 
characteristics of each: 



202 FIELD ARTILLERY MATERIEL. 

High 
Purpose. or Low. Name. 

Propelling charge in guns L Nitrocellulose, smokeless powder. 

Bursting charge, projectiles H Picric acid, explosive "D" (pow- 
der form) Trinitrotoluol. 

Blank, saluting charges L Black Powder. 

Re-inforce charges, primers L Black Powder. 

Base charge, shrapnel. L Black Powder. 

Time trains, fuzes. L Black Powder. 

Igniting charges, cannon. L Black Powder. 

Charges, submarine mines H Trinitrotoluol wet guncotton. 

Igniting elements, fuzes H Fulminate of mercury, chlorate of 

and primers. potash (potassium chlorate). 

High Explosives. The principal high explosives used 
as shell fillers in our service are: picric acid, explosive "D" 
and trinitrotoluol, or more popularly known at TNT. The 
picric acid and picrates used as shell fillers are secret com- 
positions. Mellinite, essentially picric acid alone or with 
some other substance is used as a shell filler by the French. 
It is poured into the shell in a fused state and allowed to 
harden, thus giving a very compact charge and one easily 
handled. It has the disadvantage however of forming un- 
stable compounds with the metal of the shell and great care 
must be exercised in coating the interior of the shell with a 
protective coat before pouring in the fused mellinite. Lyd- 
dite is the English equivalent of mellinite. Picric acid was 
also used by the Japanese or it may be a mixture of picric 
acid and some nitro compound. The most successful ex- 
plosive of this type is explosive "D" invented by Colonel 
Dunn of our Ordnance Department and sometimes known as 
"Dunnite." It is not fusible and must be compressed for use 
as a shell filler, being forced into the shell by compression. 
This is a disadvantage as compared to mellinite as the density 
of loading is less and weight for weight therefore less efficient. 
It is little sensitive to shock and therefore not very dangerous 
to load even under great pressure. Trinitrotoluol is also used 



EXPLOSIVES, AMMUNITION AND FUSES. 203 

as a shell filler but its chief use is in demolition work and as 
the charge for submarine mines. 

Nitrogen Compounds. It may be interesting to note that 
all of the principal explosives with which we have been dealing 
are compounds containing nitrogen. In fact the war has 
been fought with fixed nitrogen which explains the great in- 
terest taken in the various attempts to fix the free nitrogen 
of the air which is the world's great storehouse of free 
nitrogen. As nitrogen is also a necessary ingredient in the 
various fertilizers, the result to the world of a commercial 
process for speeding up the cycle of changes through which 
nitrogen passes in its life giving mission from free nitrogen 
in the air to its various compounds in the nitrogeneous animal 
and vegetable tissues is almost limitless and as usual war has 
been the incentive to speed up a process which will result in 
incalculable value to mankind. 

Classification. Guns are loaded with three kinds of 
ammunition: fixed, semi-fixed and separate loading ammuni- 
tion. In fixed ammunition the round is complete and projec- 
tile and powder loaded into the chamber at the same time. In 
semi-fixed the projectile is separate from the powder charge, 
which however is put up and loaded into the chamber in a 
container. In separate loading ammunition the powder is 
loaded into the chamber in bags. In the first two cases 
the cartridge case furnishes the means for sealing the rear of the 
powder chamber against escape to the rear of the powder 
gases. In the last case some form of obturating device is 
made a part of the breechblock furnishing a gas check to seal 
the rear of the powder chamber. 

Fixed Ammunition. All of our field guns below 5 inches 
in calibre use fixed ammunition. The powder is placed loose 
in the cartridge case, the space not filled with powder being 
stuffed with packing paper, excelsior, or felt wadding next to 



204 FIELD ARTILLERY MATERIEL. 

the projectile so as to hold the powder in contact with the 
primer. In some fixed ammunition a brass diaphragm is 
soldered to the inside of the case for the same purpose and to 
keep out moisture, (4.7" Gun). An igniting charge of black 
powder is a part of the primer and in some cases an additional 
charge is placed at the forward end of the powder space in the 
cartridge case to insure rapid ignition of the smokeless powder. 
In this case it is held in place between two quilted disks of 
crinoline. 

Semi-fixed ammunition is employed in our 6" and 4.7" 
field howitzers. The cartridge case contains three weights 
of propelling charge for firing in the three zones designed to 
give a high angle of all with these weapons. Access to the 
charge is had by tearing off the brass diaphragm closing the 
forward end of the cartridge case. By removing the first 
charge the remaining charge is that prescribed for the second 
zone, and by removing the top two charges the remaining 
charge is that of the first zone. The three charges are tied 
together and the middle charge has an igniting charge of 
black powder attached. The removal of charges is facilitated 
by the separate container for the powder charge and the round 
is more easily handled in the two parts especially in the case 
of the six-inch howitzer, where the projectile weighs 120 lbs. 
The same primer is used as in fixed ammunition, the cartridge 
case performing the function of an obturator. 

Separate Ammunition. — Obturation. The 155-mm Fil- 
loux gun and 155-mm howitzer use separate ammunition. 
In such guns there must be provided some form of a gas check 
which will prevent the powder gases from rushing to the rear 
into the threaded portion of the breechblock, as this would 
soon erode the thread sectors and render the gun useless 
beside losing a large amount of pressure in the bore. The 
device used as a gas check is called an obturator. There are 
two systems of obturation in use, named after their inventors : 



EXPLOSIVES, AMMUNITION AND FUSES. 



205 






The DeBange and the Freyre. The former is used in the 
155's. It consists of a steel mushroom head closing the rear of 
the powder chamber, the spindle of which passes through a 
central hole in the breechblock. Between the mushroom 
head and the face of the breechblock is a pad of asbestos, 

BREECH MECHANISM OF 155 GUN SHOWING 
DE BANGE OBTURATOR. 



-VENT BUSHING, 
-OBTVPATOP SPINDLE 

03TUPAT0P SPINDLE SPPlNC, 
SUPPORTING WASHER 



CP£PATING LEV&t 
HANDLE 



OPERATING LEVZW> 




BLOCK CARRIER . 
LEVER CATCH ~ 



SPEECH BLOCK 



gerv/fATv/^ spindle 






PEPCUSSION HAMMER 
LOCK BOLT 

PEPCUSSION HAMMER. 
^OPERATING SHAFT 

PEPCUSSION HAMMER 
OPERATING SHAFT QOLUtf- 



206 . FIELD ARTILLERY MATERIEL. 

paraffine and tallow, pressed into shape by a hydraulic press 
and covered by canvas or asbestos wirecloth. Split rings 
having hardened outer surfaces are fitted, one just behind the 
mushroom head and one just in front of the face of the breech- 
block. Their diameter is slightly greater in the free state 
than the conical surface of the bore where they bear when the 
breech is closed so that they always close the rear of the 
powder chamber. The pressure of the powder gases forces 
the mushroom head to the rear and this compresses the as- 
bestos pad which in turn forces the split rings to bear with 
greater force against the walls of the powder chamber thus 
securely closing the rear opening of the powder chamber. For 
more details of this device see pages 302 to 306 Tschappat's 
O & G. 

Powder Bags. Cartridge bags for separate loading are 
made of raw silk, and are sewed with silk thread. Other mate- 
rials are apt to produce flare-backs or premature explosions be- 
cause they are not entirely consumed in the bore or continue 
to burn if not consumed. The raw silk however either is 
entirely consumed or if not, the parts ignited immediately 
go out as soon as the flame is removed and do not smoulder. 
Specially treated cotton fibre bags have been tried but so 
far as I know have not as yet superseded the raw silk for 
the purpose. The gases remaining in the bore after the dis- 
charge of a charge of smokeless powder are explosive and with 
air form an explosive mixture, hence the danger upon opening 
the breech if any smouldering particles remain in the bore. 

Primers. The devices for initiating explosions of pro- 
pelling charges in military guns are called primers. With 
fixed and semi-fixed ammunition the primers are seated in the 
base of the cartridge case. In the case of separate loading 
ammunition the primers are inserted separately in the breech- 
block, the expanding gases of the detonated primer forcing 



208 FIELD ARTILLERY MATERIEL. 

the walls of the primer case tightly against the bore through the 
breechblock and thus sealing this channel of escape for the 
gases from the powder chamber. This necessitates a much 
larger and stronger case for separate loading primers than for 
those inserted in the base of a cartridge case. 

Classes of primers. Primers are divided into three classes 
according to the method by which they are fired: (a) friction 
primers, (2) electric primers, (3) percussion primers. Com- 
bination primers are made which may be fired by any two of 
these methods, usually electric and one of the others. The 
characteristics of a good primer are, certainty of action, 
safety in handling, no deterioration in storage, simplicity in 
construction and be cheap to manufacture. They are also 
divided into obturating and non-obturating depending upon 
whether they close the vent during discharge or not. 

Primer pressing. Primers for fixed ammunition are in- 
serted in the base of the cartridge cases by means of a special 
press for this purpose. The primer body is a trifle larger than 
the seat in the cartridge case provided. This seat is rough 
bored to a diameter less than the finished size and then man- 
dreled to finished dimensions with a steel tapered plug. This 
process toughens the material of the case around the primer 
seat and prevents the expansion of the primer seat under 
pressure of the expanding gases. 

Percussion primers. Except for very heavy siege guns 
and railroad artillery the guns handled by the Field Artillery 
use percussion primers. The 110-grain percussion primer is 
the one in use in our service and as typical will be described. 
The charge consisting of 110 grains of compressed black powder 
makes the charge burn like a torch rather than explode, which 
facilitates the ignition of the charge of smokeless powder, with 
which the flame comes in contact. The diametral holes 
spray the flame in several directions thus insuring ignition at 



EXPLOSIVES, AMMUNITION AND FUSES. 209 

many points simultaneously. The percussion element consists 
of a percussion primer cup, the percussion composition and 
an anvil, all of which are assembled together in a cup in the 
rear face of the primer case. The percussion composition 
is made up of chlorate of potash, sulphide of antimony ground 
glass and sulphur. A blow upon the cap by the firing pin 
detonates the percussion composition and the flame from this 
detonation ignites the black powder which in turn explodes 
the charge of smokeless powder. 

The General Shape and Nomenclature of Projectiles. 

The reason for the particular shape of shells may not be 
clear to all. In the first place all matter has the property 
known as inertia, which we may define as that tendency of 
matter to remain in a state of rest or to continue at a uniform 
velocity if in motion. It offers a resistance to any change in 
the state of either rest or motion whether of amount or direc- 
tion. Consequently when we apply a sudden and tremendous 
force to the base of a projectile by means of the expansive 
force of exploding powder gases, there will be set up in the 
metal a resistance to this force in which every particle of the 
projectile will resist by an amount proportional to the mass 
of particles beyond the point of application of the force to 
itself. The actual force will be proportional to the weight 
and acceleration produced by the applied force in the projec- 
tile. This explains the reason why the walls of the projectile 
are thicker near the base. It also explains the method of 
calculating the thickness of walls, for if we know the weight 
at any cross section and the co-efficient of strength of the 
metal we may calculate the thickness of walls necessary to 
withstand the pressure for any given muzzle velocity which is 
fixed by other considerations. It explains also the preference 
for steel in projectiles as for the same weight the steel is much 



EXPLOSIVES, AMMUNITION AND FUSES. 211 

stronger making it possible to throw a greater amount of 
shrapnel or high explosives in shell. 

The necessity for compact loading, especially in the case 
of high explosive shell is also noted as otherwise the shock 
due to inertia would break up the charge and perhaps cause 
a premature explosion. Hence it is very necessary to guard 
against airholes in filling shell cavities. 

In order to secure regular and uninterrupted movement 
of the projectile through the bore it is necessary that the 
projectile and bore have the same geometric axis. Also the 
projectile must be seated exactly and uniformly for succeed- 
ing rounds in its seating in the bore. This latter is necessary 
in order that the powder chamber may not vary as this would 
give irregular pressures. The liability of strapping the rota- 
ting bands or setting off the fuze in certain kinds of fuzes are 
also explained by inertia. It might even cause sufficient 
shock to detonate the charge in the shell. The remedy is 
accurate seating of each projectile by reason of trained gun 
crews using the same amount of force at each ramming. 
The first condition, coincidence of axes, is obtained by means 
of the ogival head which has a diameter some tenths of a 
millimeter smaller than the diameter of the bore, and serves 
as a front support for the projectile while the rotating bands 
center it in rear. Were it not for the bell the projectile, held 
only by the soft material of the rotating band, would wabble 
in its travel through the bore and tumble soon after leaving it. 
It is also necessary that the center of gravity of the projectile 
be on its geometric axis. Otherwise it will travel on a spiral 
of the same pitch as the grooves and knock the tube walls 
as it travels through the bore and without the support of the 
bell might cause a premature explosion by actuating the 
fuze. 




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-EOTATinS BAMD. i STEEL SHELL. 




COMriOPI 3TELL ^HELL MODEL Of 1905. 



LOOSE BLACK POWDEJ?. 
STEEL DIAPiiPAGM.- 



-SHPAPN EL BALLS, i— CEJTTRALTUBE. , — STEEL HEAD 
r-GUn COTTOn. p-STgEL CASE 

•MATRIX. 



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BJ2ASS COVEC. 




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l nnl.n.1 I J I I I I 1 I I :F=1 3 6 -£3.-70. 



4.7" Gun Ammunition. 



214 FIELD ARTILLERY MATERIEL. 



Three-inch Ammunition. 



Fixed ammunition is used in the 3" field guns, and is 
made up with either common shrapnel, high explosive shrapnel, 
or common steel shell. The rounds as made up vary in length 
with the type of projectile used. The ammunition chests of 
the battery are of sufficient size to take any one of the rounds 
furnished, so that the number of each kind to be carried is a 
matter for regulation by proper authority. Each round is 
issued with projectile filled and fused. The weight of the 
projectile is 15 pounds, and the total weight of one round is 
18.75 pounds. The components of one round are the car- 
tridge case with primer, the powder charge, igniter, projectile 
and fuze. 

The cartridge case. — The cartridge case is a solid drawn- 
brass case 10.8 inches long; it has a capacity of 66.5 cubic 
inches, and weighs, with primer, 2.25 pounds. A circular 
groove is cut in the base of the cartridge case and the groove 
is painted red for high explosive shrapnel, yellow for common 
shrapnel, and black for high explosive shell. 

The primer. — The percussion primer, known as the "110- 
grain percussion primer," contains an igniting charge of 110 
grains of black powder in addition to the essential elements of 
a percussion primer. The purpose of the black powder is to 
insure the ignition of the smokeless powder charge in cartridge 
case. 

The powder charge. — The powder is a nitrocellulose pow- 
der composed of multiperforated (7 perforations) cylindrical 
grains, each 0.35" long and 0.195" in diameter. The charge 
varies slightly for different lots of powder, but is approximately 
24 ounces. The charge gives a muzzle velocity for shrapnel 
of 1,700 feet per second (1600 f/s for shell) with a maximum 
pressure in the bore not exceeding 33,000 pounds per square 
inch. At the front end of the cartridge case there is an ig- 



.-—Jfttse Cover: 
\ — -J2a.se Covev Cfroove and calking were 

r-RotaUng Band. r ~Steel Shell. 

r _^^_ — Base Detonating J^ltze, jCfedium Caliber 




C^o/n/Tion Steel Shell. 

I Lubricating and Crimping Grooves. 



rLoose Black Powder: 



tfteel Diap7iragm. 
vShrxzpnel 23alls. 
I ^ACalrix. 
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^Sleel Case. 

I Bourrelet. 



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Jfi qh Explosive Shrapnel. V 






y & 



\; 



3" AMMUNITION 



EXPLOSIVES, AMMUNITION AND FUSES. 215 

niter of black powder weighing about 34 oz. which assists in 
the uniform ignition of the smokeless powder charge. 

The projectiles. — All projectiles have a copper rotating 
band 1.2" from the base. This band engages in the rifling 
of the bore of the piece, and gives the projectile a rapid 
rotation about its long axis during flight. This causes it to 
travel straight, point on, without tumbling. 

Common shrapnel. — The common shrapnel is a base- 
charged shrapnel fitted with a combination fuze. The case is 
of steel with solid base. The shrapnel filling is composed of 
252 balls, each approximately 167 grains in weight (42 to the 
pound). The balls are approximately 0.5" in diameter. The 
balls are poured around a central tube and rest upon a steel 
diaphragm, the interstices containing a smoke-producing ma- 
trix. The bursting charge consisting of 2% oz. of black 
powder is in the base and is covered by the diaphragm which 
supports the central tube, affording a conduit to the flame 
leading from the fuze to the bursting charge. 

In action the case is not ruptured upon the explosion of 
the bursting charge; the head is stripped and the balls are shot 
out of the case with an increase of velocity of about 274 feet 
per second. The remaining velocity of the shrapnel at 6,500 
yards is approximately 724 feet per second and the time of 
flight 22 seconds, so that at that extreme range, with the 
increase of velocity due to the bursting charge, this shrapnel 
with 21-second fuze will be effective. The weight of the 
shrapnel with fuze is 15 pounds. 

Shrapnel is a projectile containing a great number of 
hardened steel balls, each approximately \" in diameter, 
which may be projected from a point in the air (called the 
point of burst) close to but short of the target. Each ball is 
capable of killing a man or horse at a distance up to 250 or 300 
yards from the point of burst. Taken collectively, the paths 



216 FIELD ARTILLERY MATERIEL. 

of these balls form a cone, called the cone of dispersion. The 
ground section of this cone is elliptical in shape with its longer 
axis approximately in the plane of fire. At mid-range when 
burst at normal height of burst (H. B.=3 mils), the dimensions 
of this area are approximately 20 yards wide by 250 yards 
deep. These dimensions will however vary with the angle 
of fall, the height of burst, the slope of the ground at the target, 
and the relation between the linear and the rotational velocities 
of the shrapnel at instant of burst in the air. A 3-mil H. B. 
is chosen because this gives an average density of 1 hit per 
square yard of vertical target area. An infantry skirmisher 
(standing) with his interval occupies approximately 1 square 
yard. 

Shrapnel has very little effect upon material objects. 
It is very effective against personnel not protected by cover, 
or to search an area which is known to be occupied, or which 
must be traversed, by hostile troops. 

Ehrhardt High-explosive shrapnel. — The Ehrhardt high- 
explosive shrapnel is fitted with a combination fuze and a high 
explosive head. The case is drawn steel with solid base. The 
shrapnel filling is composed of 285 balls, each approximately 
138 grains in weight (50 to the pound). The balls are poured 
around the central tube and rest upon the steel diaphragm, 
the interstices containing a matrix of high explosive. 

In time action (burst in air), the case is not ruptured upon 
the explosion of the bursting charge, but the head is forced out 
and the balls are shot out of the case with an increase of ve- 
locity of from 250 to 300 feet per second. In the meantime 
the head continues its flight, detonating on impact. 

If the fuze be set at "safety" or for a time greater than the 
actual time of flight, this shrapnel may be used in lieu of high- 
explosive shell. Upon impact a high-explosive shrapnel is 
detonated by means of the percussion element of the combina- 
tion fuze, the head being detonated first, which detonation 



EXPLOSIVES, AMMUNITION AND FUSES. 217 

causes the sympathetic detonation of high-explosive matrix 
surrounding the balls. 

Common steel shell. — This steel shell is high-explosive 
and fitted with a base detonating fuze. The case is hollow 
and made of drawn steel. It is provided with an ogival head. 
The steel shell contains a bursting charge of 13.12 ounces of 
Explosive D. The weight of the shell with bursting charge 
and fuze is 15 pounds. The shell is always issued filled and 
fuxed. 

This shell bursts on impact and with great force exerted 
in all directions. It is a powerful instrument for the destruc- 
tion of material objects such as guns, intrenchments, houses, 
stone walls, etc. The effect, however, is very local. 

Frankford Arsenal combination fuzes. — These fuzes are 
point fuzes with combination time and percussion elements for 
use with common shrapnel. They are of the type known as 
the ring or "dial" fuze, in which the time train is set by turn- 
ing a graduated ring which carries part of the train. These 
fuzes may be reset as often as desired. 

Ehrhardt combination fuze for high explosive shrap- 
nel. — This fuze is similar to the Frankford Arsenal Combina- 
tion time and percussion fuze but in addition contains a high 
explosive head and detonating element. Due to this arrange- 
ment, both the projectile and the high explosive head have 
a high-explosive shell effect when striking on impact. 

The service base detonating fuze. — The details of the 
detonating fuze and the composition of the detonator are kept 
secret. A detonating fuze is necessary in order to produce a 
higher order of explosion by causing an instantaneous con- 
version of the high explosive compound called " Explosive D" 
with which the shell is charged. If an ordinary percussion 
fuze were used only an ordinary explosion would be produced 
as in the explosion of black powder. 



218 FIELD ARTILLERY MATERIEL. 

Preparation of blank metallic ammunition. — Blank me- 
tallic ammunition will always be assembled under the per- 
sonal supervision of a commissioned officer, who will be held 
responsible that it is prepared in the manner prescribed. (G. 
O. 9, War Dept., Jan. 11, 1908.) 

For this purpose there are issued blank-cartridge cases, 
black powder in bulk, tight-fitting felt wads, rubberine, or 
other quick-drying paint, primers, etc. 

Before assembling, the cartridge cases should be care- 
fully inspected to see that they are in sound condition and 
thoroughly clean and dry. They should also be tested by 
trying them in the gun, to determine whether they have be- 
come deformed. Any cases that do not readily enter the 
chamber in the gun or that are otherwise seriously deformed 
should be laid aside for resizing. After inspecting the car- 
tridge cases the blank ammunition should be prepared as 
follows: 

(a) Insert the primers with the primer-inserting press. 

(b) Pour into the cartridge case the proper weight of 
black powder and shake it down well. 

(c) Insert the felt wad and press it down hard until it 
rests squarely on the powder charge. 

(d) Give the upper surface of the felt wad and the inside 
of the cartridge case just above the wad a good coat of the 
rubberine or other quick-drying paint furnished for the pur- 
pose, using a brush, and allow the case to stand until this coat 
is dry. Then apply another coat of rubberine paint in a sim- 
ilar manner. The object of using rubberine paint, which is 
strongly adhesive, is to thoroughly seal the joint between the 
wad and the case to prevent any powder grains from leaking 
out, and at the same time to firmly hold the wad in place. 



EXPLOSIVES, AMMUNITION AND FUSES. 219 

The reloading and cleaning outfit. — This outfit con- 
sists of the following parts, and is furnished to each battery: 

Primer-inserting press, small Hammer 

Bushing Case holder 

Powder measure, saluting Case-holder stand 

Decapping tool, with guide Storage chest 
Cleaning brush 

The bushing is used in the primer-inserting press for the 
insertion of new primers. 

The decapping tool and case holder and stand are used for 
removing exploded primers from the cartridge cases. A light 
blow on the rod with a piece of wood or the bronze hammer 
generally removes the primer. 

A powder measure to suit the saluting charge for the gun 
is furnished, and when level full holds the required charge. 

The cleaning brush is furnished for cleaning the cartridge 
cases after they have been used and should be ordered to suit 
the size of case for which intended. 

Care of Cartridge Cases. — As soon after firing as prac- 
ticable the exploded primers should be removed from the 
cartridge case by means of the decapping tools furnished with 
the reloading outfit. The case should then be thoroughly 
washed in a strong solution of soft soap and soda to remove 
all powder residue. It should then be thoroughly dried. 

If the cartridge cases are carefully cleaned and washed 
immediately after firing, not only will less labor be required 
but the life of the cartridge case will be greatly prolonged. 

A good solution for washing cartridge cases may be pre- 
pared by using ingredients in the following proportions : 1 gal- 
lon of water, 2\ ounces of soft soap, 5J ounces soda. The 
mixture should be boiled and stirred until the ingredients are 
entirely dissolved. 

In washing cartridge cases this solution should be used 
hot and in sufficient quantity to completely immerse the cases. 



220 FIELD ARTILLERY MATERIEL. 

Neither acids nor solutions of acids will be used for clean- 
ing cartridge cases. 

Precautions to be Observed with Fixed Ammunition. 

(a) Do not unnecessarily expose ammunition to the 
sun or load it into a warm gun before time for firing; if this is 
done, erratic shooting will result. 

(b) Handle carefully, otherwise cartridges may become 
deformed and cause jams. 

(c) Never use force or any implements on the base of 
the cartridge in loading. 

(d) See that fuzes set at safety or are provided with 
waterproof brass cover for transport. 

(e) Do not fire ammunition which has been under water 
with the waterproof brass cover removed. 

(f) Both service and blank ammunition should never 
be carried in the battery at the same time. If conditions are 
such that both may be used in exercises, only one kind should 
be in the firing battery; the other should be under lock and key 
outside the firing position. 

(g) Misfires and hangfires are of exceedingly rare oc- 
currence. In case of a failure to fire, the firing handle should 
be pulled again in order to snap the trigger. If this fails to fire, 
the breech should not be opened until after the expiration of at 
least one minute, when the round or cartridge should be re- 
moved and placed to one side. Defective ammunition, car- 
tridges and primers should be reported. 

With Blank Ammunition. 

Firing with blank ammunition will be greatly facilitated 
by a careful observance of the following: 

(a) Before firing, a careful examination should be made 
of the assembled rounds to see that the felt wads have not 



EXPLOSIVES, AMMUNITION AND FUSES. 221 

become displaced or the cartridge cases dented or deformed by 
careless handling. If the cartridge cases have been properly 
resized and are clean, no difficulty should be experienced in 
inserting them in the gun, provided the chamber of the latter 
is clean. The continued insertion of cartridge cases that are 
not clean causes an accumulation in the gun chamber which 
may make the insertion of subsequent rounds difficult or 
impossible. 

(b) In firing blank ammunition the gun chamber will 
be sponged after each round with a damp sponge, to extinguish 
sparks and remove powder residue resulting from the previous 
round, before the insertion of another round. 

(c) Care will be taken to see that the sponges are not 
worn and that they thoroughly fit the chamber. The inter- 
val between rounds in firing blank ammunition should be suf- 
ficient to allow thorough sponging of the chamber and exam- 
ination to ascertain that all sparks have been extinguished. 

(d) Wads for the preparation of blank metallic ammu- 
nition are made to tightly fit in the cartridge case. No wads 
should be used that are not a tight fit in the case. 

FUZES. 
Principle of operation. — We have just learned something 
of the force of inertia in connection with a projectile. Most 
fuzes are actuated by this force. From our knowledge of the 
trajectory we know that usually a projectile does not strike 
on its nose. Therefore we cannot devise our fuzes to work 
like the driving of a nail into a board. The striking element 
is the anvil and is a fixed pointed spur against which a sliding 
element containing a fulminate strikes. The sliding block 
carries a small charge of black powder which is set off by the 
fulminate, thus igniting the train which leads to the high 
explosive charge detonator. Were this sliding block left free 
to slide back and forth at all times it would be unsafe to trans- 



222 FIELD ARTILLERY MATERIEL. 

port the fuze, as it might be set off by accident. There must 
be therefore some means of holding it safely away from the an- 
vil until it is desired to detonate the charge. There are thus 
two conflicting conditions to be met: safety during transporta- 
tion and sensitiveness at the point of departure. It may not 
be understood at first why sensitiveness at the point of de- 
parture should be a condition to be met. Suffice it to say that 
all fuzes are designed to arm at discharge or soon after leaving 
the bore for they must be ready to act at any time after leaving 
the muzzle. Were they to be safe during flight they might be 
so safe that the remaining velocity would not be sufficient 
to set them off. All fuzes are designed to arm as we say either 
during travel through the bore or immediately after. 

Methods of Arming. 

Spring method. — Let us suppose that after our projec- 
tile has started on its way the sliding block is free to move with- 
in a cavity at the forward end of which is the anvil. If the 
projectile comes to a sudden drop or even sudden reduction of 
velocity the block if unrestrained will, according to the prin- 
ciple of inertia, keep on going till something stops it. The 
something in this case is the anvil and the fulminate cap is 
set off. But it is not so simple. For while the projectile is 
in flight it is acted upon by the air resistance and slows down 
but the block in the cavity of the head is not subjected to this 
resistance. It therefore gains on the projectile or creeps 
forward in the cavity unless restrained as it is by a spring. 
Now one more point and this type of fuze is complete. We 
supposed that our block was free to slide. For safety's sake 
it is pinned to the cavity. Again we call upon inertia to bread 
the pin so as to leave the block free to slide. The strength of 
the pin is calculated so that the force of inertia of the mass of 
the block is greater than the resistance of the safety pin and 
when the projectile starts the pin breaks and the spring forces 



EXPLOSIVES, AMMUNITION AND FUSES. 223 

the block to the rear of the cavity until the sudden stop of the 
projectile permits the block to slide forward as explained. 
Such a fuze requires a comparatively high initial velocity and 
is not adapted to howitzers using low muzzle velocities. 

There are three other methods in use to arm the fuze. 
They are inertia of a sleeve; centrifugal force and powder 
pellet system, that is, combustion of a grain of powder holding 
the sliding block from the anvil by means of an arm resting 
against the unburned powder grain. These are more sensitive 
than the type described. 

In the first system, a sleeve fitting around the plunger 
carrying the cap slides to the rear by inertia when the projec- 
tile starts and two clips engage in notches on the plunger body 
making the sleeve and plunger thereafter move as one body, 
they are thus held together by a plunger spring which before 
arming held the plunger away from the anvil. The safety 
spring held the sleeve and plunger away from the anvil and 
after arming prevents forward creeping by the plunger and 
sleeve now locked together. Upon striking, the plunger and 
sleeve move forward as one body and the cap strikes the anvil. 

In centrifugal systems the primer plunger is kept safely 
away from the anvil by a lock which is kept in place by springs. 
When the rotational velocity reaches a certain point the force 
of the springs is overcome by the centrifugal force and the 
locks are thrown aside or opened and the plunger is free to 
move forward on impact. 

In the powder pellet system (the one largely used by the 
Germans) there is a well or channel filled with compressed 
powder, this is set off by a fulminate cap which is fired by iner- 
tia, a small plunger-anvil striking the cap. When the powder 
is consumed it leaves a channel into which an arm attached to 
the sliding block carrying the igniting fulminate for the charge 
may slide, thus permitting the block to slide forward to the 



224 FIELD ARTILLERY MATERIEL. 

anvil fixed in the forward part of the cavity. It is held from 
creeping forward after the compressed powder is burned by a 
safety spring, thus insuring sufficiently hard an impact to set 
off the cap. 

Heretofore in our service the fulminating cap has been 
fixed and the plunger carried the anvil or as we call it the 
firing pin. Such is now the system in our base detonating 
fuzes, and in our combination fuze. 

The new point detonating fuzes are patterned after the 
French and are practically French fuzes. 

Fuzes Classification. 

Fuses are classified as: 

(a) Percussion if it acts on impact, producing a low 
order of explosion. 

(b) Time when it acts in the air at a certain point of the 
trajectory. 

(c) Combination if it is able to act in the air or upon 
impact. 

(d) Detonating when it contains a fulminate which will 
bring about detonation upon impact. 

The detonator may be separate or incorporated in the fuse. 
For the 75-mm gun and the 155-mm howitzer it forms a part 
of the fuze. 

Many fuzes are armed on set-back. An exception to this 
is the long detonating fuse, MK 111, which is armed by the 
unrolling of a brass spiral holding together two half rings made 
of steel so fitted as to prevent the anvil and the head of the fuse 
from getting close together. The spiral unrolls when the 
rotational velocity of the projectile reaches a certain speed, 
thus drawing away the two steel rings and arming the fuse. 

It is of great importance that the spiral spring be not 
unrolled during transportation or storage. This is prevented 
by winding a tape of tarred canvas around the spirals, the 



EXPLOSIVES, AMMUNITION AND FUSES. 227 

head being covered by a thin band of tinfoil. Just before 
loading the projectile the head and tape are removed by pulling 
the free end of the tape. 

The following precautions concerning fuses must be rigidly 
observed to prevent grave accidents : 

1. All detonators and detonating point fuses must be 
fitted with a felt washer underneath, thus insuring proper 
seating in the central tube. 

2. Never disassemble a fuse by unscrewing. 

3. Any fuse, the parts of which have become accidentally 
unscrewed, must be destroyed at once. If fired it may cause 
a premature burst; if handled a grave accident may result. 

4. Any fuse or projectile which has been fired is danger- 
ous, because it may then be able to detonate by a very slight 
shock. It is forbidden to touch it. 

5. Never remove the tin hood from the long fuse before 
having screwed the fuse in the central tube. 

6. After having removed the tin hood, be sure that the 
spiral is in its proper position. Never use a long fuse with- 
out the spiral. 

7. Be sure the men understand that this spiral must not 
be removed. It has happened that men have removed this 
spiral, thinking that it was a device similar to the safety ring 
in trench mortar fuzes, MK VII E. 

8. See that the ring of the long fuze which connects the 
powder train to the fuze body cannot be unscrewed. If it 
can be unscrewed the fuze should be sent back to the depot. 

9. If it is necessary to remove a shell with a long fuze 
by means of the rammer, be sure to have a special rammer cup 
in the shape of a hollow cylinder of wood which will fit between 
the shell and the rammer. 

10. Time and combination fuzes cannot be made abso- 
lutely water-tight; the cover must therefore not be removed 
until the projectile is about to be loaded. 



228 FIELD ARTILLERY MATERIEL. 



Fuse Tables. 

Tables showing American and French fuses to be used 
by our Field Artillery, with information concerning markings, 
color, time of delay, size of fuse, etc. 



EXPLOSIVES, AMMUNITION AND FUSES. 



229 



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EXPLOSIVES, AMMUNITION AND FUSES. 233 

Notes on Ammunition Marking. 

Marks on H. E. Shell. These are of two kinds. 

(a) Stamped marks made with a steel punch on the 
body of the projectile just above the rotating band. These 
refer to the manufacture of the projectile. 

(b) Painted marks or bands which are clearly visible. 
They refer to the loading, to the weight of the projectile and to 
the special purposes for which the projectile is to be used. 

Painted marks referring to loading are found on the ogive. 

H. E. shells are usually painted red. 

Marks referring to weight are painted in black just above 
the rotating band, as follows: 

L. — very light. 
+— light. 

+ H normal. 

+ + H heavy. 

+ + + H very heavy. 

A white cross above these marks means that a plate has 
been welded on the base. These marks are also painted on 
the boxes. 

Shells fitted with cartridge cases (fixed ammunition) are 
not painted below the rotating bands. 
Special Shell. 

Incendiary shells. — These incendiary shells are filled with 
some flame-producing liquid, alumino thermic charge or in- 
cendiary cylinder composed of slow burning linstock and string 
strongly impregnated with saltpeter. 

Markings. — Green with red ogive. 

All shells containing black powder are more or less in- 
cendiary. Percussion shrapnel is incendiary. 

Star Shells. — For 155 howitzer. Upon bursting, they 
liberate eight white stars fitted with silken parachutes. The 
stars are projected backward through the base of the projec- 



r 6ASE COVERS 

LEAD. DISC (-ROTATING BAND r STEEL SHELL 



BOOSTER 



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STEEL HEAD 

COMBINATION FUSE 
BRASS COVER' 




75 MM. SHRAPNEL 



CASE 



CAPACJTr-APPROX 65.SCUINS 



— m 




r-SHEIX- 



75 MM. FIELD GW* CARTRIDGE. CASE 



BASE OF CASL 




75mm Ammunition. 



EXPLOSIVES, AMMUNITION AND FUSES. 235 

tile at the point of burst. The parachutes open, the stars 
descending very slowly, illuminating the surrounding objects 
for about 45 sec. The best height of burst is about 300 m. ; 
the burst interval should not be over 300. These shells are 
also incendiary. Markings: a blue star and an "E." 
Gas shells are either toxic or tear-producing. 

(a) Toxic shells are numbered either 4 or 5. The liquids 
4 and 5 volatize immediately upon contact with the air. The 
gases are quickly diffused and easily carried by the wind. 

Effect. — Liquid 4 acts immediately and is felt instantly. 

Liquid 5, on the contrary, works more slowly and its 
effects are apparent only after several hours. Markings: 
Green with white bands, and numbers 4 or 5 on the ogive. 

(b) Tear shells. — These shells are numbered 11, 12 and 
13. They are filled with two liquids, either mixed or separated, 
one liquid being tear producing, the other smoke producing. 
When the shell bursts, a greater part of the liquid is volatil- 
ized, the remainder being projected to the ground in small 
drops which volatize with variable speed. Markings: Green 
with numbers 11, 12 or 13 on the ogive. 

Tracer shell. — This shell is fitted with a time fuse which 
ignites the inside charge, the flames of which pass through the 
holes in the ogive thus tracing the trajectory. Tracer shells 
are used in fire for adjustment on aircraft. They are also 
incendiary. Markings: White with blue ogive. Letter "T" 
painted on body. 

PRECAUTIONS IN SEPARATE LOADING PROJECTILES. 

All projectiles must be seated accurately and carefully 
in loading, otherwise not only inaccurate fire will result but 
also premature detonations may occur. 

Rotating bands should be smoothed and lightly greased 
just before loading. In transport and in storage the bands 
should be protected by rope bands, straw tithes, etc., to pre- 
vent deformation. 



236 FIELD ARTILLERY MATERIEL. 



CHPTER XIII 
CARE AND PRESERVATION. 

OILS AND CLEANING MATERIAL, TOOLS AND 
ACCESSORIES FOR ARTILLERY MATERIEL 
WITH THEIR USE. 

In order that all parts of the materiel may funtion easily, 
it is necessary that all the working and bearing surfaces may 
be properly cleaned and lubricated with the appropriate 
lubricant. Where such surfaces are not directly accessible, oil 
holes are provided; these holes should be kept free from grit 
and dirt. Except during oiling, they should be kept fully 
closed by the means provided. 

For use in service, for the cleaning and preservation of 
this materiel, the ordnance department issues hydroline oil, 
lubricating oil, clock oil, vaseline, sperm oil, coal oil, neat's- 
foot oil and light slushing oil. Each of these oils are suited 
for the particular purpose for which it is issued, as stated be- 
low, and care should be taken that it is not used for other 
purposes. 

Hydroline oil. — Used in the recoil cylinders of the carriage 
and for no other purpose. Never used as a lubricant. It is 
characterized by its low freezing point and its non-corrosive 
action on metals. 

Lubricating oil (Engine oil Number 1). — A light petrol- 
eum oil used exclusively in all oil holes of the materiel, and in 
lubricating such parts as wheels and axles, guns and cradle 
slides, cradle pintle and socket elevating and traversing 
mechanisms, exterior of cylinders, brake bearings, hinges, 
different surfaces of breechblocks, threads, breech recess, et 
cetera. 



CARE AND PRESERVATION. 237 

Clock oil. — Used on the spindle and all gearings of the 
Battery Commander's telescope, bearings of the panoramic 
sight, range quadrants and fuze setters. In all cases clock 
oil should be used only when the instruments mentioned are 
disassembled for cleaning. It should be applied by dropping 
from the end of the dropper attached to the end of the cork. 
In case of emergency, use as a substitute either sperm oil or 
Engine oil No. 1, in the order mentioned. 

Vaseline (Petrolatum). — The heavy petroleum oil free 
from rosin. Used on the worm gears and the worm racks of 
the panoramic sight, the hand and bracket fuze setter, B. C. 
telescope, and on the micrometer screw and bushing of the 
quadrant. The spare parts of the breech mechanism should 
also be coated with vaseline and each piece then wrapped in 
paper to prevent the oil from being rubbed off. 

Sperm oil. — A lighter lubricant than the lubricating oils, 
and may be used on the gears of sights, fuze setters, ranges, 
quadrants, parts of revolvers, et cetera; lubricating oil may 
also be used on such parts. It is also used as a temporary 
rust preventive. Its low viscosity and light body make it 
unsuitable for this purpose for more than a few days. 

Coal oil. — Used for cleaning purposes. In the field it may 
be used for lanterns. Coal oil for general illuminating pur- 
poses is furnished by the quartermaster department. 

Neat's-foot Oil. — An animal oil used for softening and 
preserving leather. Applied with a moistened cloth to the 
flesh side of moistened leather. 

Light slushing oil. — The heavy petroleum oil similar to 
cosmic. Used as a rust preventive. Essentially a mineral 
oil containing a large per cent of rosin. Prescribed for use 
in the protection and preservation of all bright or unpainted 
of steel or iron on all parts of the equipment when the materiel 
is to remain unused for an appreciable length of time. Its 



238 FIELD ARTILLERY MATERIEL. 

use as a lubricant for mobile artillery is forbidden. Before 
applying the slushing oil to any surface, the parts should be 
thoroughly cleaned so as to be free from rust, coal oil, lubricat- 
ing oil, et cetera, as their presence will cause rusting under the 
slushing oil. The slushing oil should then be applied in a 
thin, uniform coat, since this is all that is necessary to give 
good protection. Except in very cold weather it can be 
applied by using a paint brush as when painting, in cold 
weather it should be applied by stippling — that is, by holding 
the brush perpendicular to the surface to be coated and then 
tapping the surface with the point of the brush. It can be 
applied through the bore of the gun by a slush brush issued 
for that purpose. In cold weather it should be warmed be- 
fore used in the bore of the gun. It may be readily removed 
by burlap or waste dipped coal oil. 

Borax. — Issued for use as a flux in welding. 

Lavaline. — A metal polish issued interchangeable with 
Gibson's soap polish. Used on bits and collars. 

Lye, powdered. — When dissolved in water, one pound to 
six quarts with sufficient lime to give a consistence of paint, 
is used to remove old and blistered paint. 

Napthaline. — A moth preventive, effective only after 
eggs and grubs already present have been removed. Used 
in the storage of blankets, et cetera. 

Polish, Gibson's Soap. — A metal polish issued inter- 
changeably with lavaline. Used on bits and collars. 

Paint, rubberine. — Used in connection with loading 
ammunition in accordance with instructions regarding the 
same. 

Primer, brown enamel. — A hard, quick drying enamel 
used for painting parts of horse collars, draft springs, et cetera. 



CARE AND PRESERVATION. 239 

Sal Soda, Bicarbonate of Soda. — A saturated solution of 
soda and water makes an alkaline solution that will not rust. 
The solution must be saturated, that is, at least 20% or one- 
fourth pound of soda (6 heaping spoonfuls to one cup of water). 
This solution is an effective solvent of powder fouling and 
should always be used after firing, whether metal fouling 
solution is to be used or not It reduces the labor of cleaning 
with oil alone by more than half. Used also in a weaker 
solution (one-half pound to 8 quarts of water) in washing 
surfaces to be painted and to remove dirt and grease. 

Soap, H. & H. — A neutral naphtha soap used in washing 
blankets, web and cloth equipment. Applied in the form 
of a solution (one cake to 9 cups of hot water). If for any 
cause this soap is not obtainable, a good laundry soap (ivory 
or equal) may be used, but in no case should yellow soap 
containing a large percentage of alkali be used. 

Soap, castile. — An alkaline soap used in cleaning leather 
equipment. Applied on a moistened sponge. 

Soap, saddle (Hollingshead). — A soap used as a dressing 
for leather equipment. Applied with a thick lather on a 
moistened sponge. 

Swabbing solution, contains. — Ammonium persulphate, 
60 grains or one half spoonful smoothed off. Ammonia 28%, 
6 oz. or 3/8 of a pint or 12 spoonfuls. Water, 4 oz. or 1/4 pnt 
or 8 spoonfuls. Dissolve the ammonium persulphate in the 
water and add the ammonia. Keep in a tightly corked bottle. 
Pour out only what is necessary at a time and keep the bottle 
corked. 

TOOLS AND ACCESSORIES. 

In the repair of all equipment, it is literally true that "a 
stitch in time saves nine," and that a timely repair will save 
the entire article. 



240 FIELD ARTILLERY MATERIEL. 

Tool Kits will be kept complete and serviceable ; edges of 
cold chisels free from nicks; drifts and punches properly 
shaped immediately after using; and files kept clean. 

To prevent unscrewing, copper wire is used to lash nuts 
and other threaded parts which are not secured by split pins. 

Contents of Leather Pouch for Spare Parts (carried in 
Trail Boxes of 3-inch Guns) : — 

For Breechblock — 

50 Split pins 

1 Block latch and spring 

1 Firing pin and spring 

1 Firing pin sleeve 

2 Handy oilers, 5-16 inch 
1 Hinge pin catch 

1 Lever latch spring 

1 Locking bolt, nut and pin 

1 Locking bolt spring 

2 Oil hole covers with screws 
1 Pallet pin 

1 Sear 

2 Trigger shaft detent 
For Hand Fuze Setter — 

2 Corrector scale screws 

1 Guide plate lock screw 

2 Index bar screws 

1 Index plunger and spring 

2 Oil hole screws 
1 Range index 

3 Range ring screws 
1 Stop pin screw 

For Bracket Fuze Setter — 

1 Corrector scale screw 

3 Guide screws 

4 Housing screws & split washers 
1 Knob washer 

1 Range worm crank & knob taper pin 

1 Range worm crank handle 

2 Range ring screws- 

3 Split pins (0.125). 



CARE AND PRESERVATION 241 

1 Spring and spring cover with screw. 

2 Stop pins with rivets 
For Cylinder — 

1 Drain-plug, cylinder 

1 Elevating & traversing lock spring. 

1 Filling plug (piston rod). 

5 Rings Garlock packing, 3/4 in. 

Special Wrenches, Spanners, other tools and accessories 
will be used only for the purposes for which they are intended. 
This purpose is usually stamped upon the tool. 

In assembling or disassembling parts of the materiel, 
no part will be struck directly with a hammer. If force is 
necessary, a piece of wood or copper should be interposed be- 
tween the hammer and the part struck. All nuts are provided 
with split pins as keepers. 

A pair of wire cutting pliers is provided for use in pulling 
split pins, cutting wire lashings, etc. When a nut is assembled 
the split pin should always be inserted and properly opened. 

Axes, hatchets, picks, pick mattocks and shovels are 
carried on the carriage for use in the field and will not be put 
to other uses. The working edges will be kept bright and 
lightly oiled, the edges being sharpened if intended for cutting, 
or smooth if intended for digging. Deformed blades, edges or 
points should be straightened at the anvil and forge or in a 
vise. Shovel points are straightened with a hammer on a 
block of wood. 

The side edges of shovel blades should not be used as a 
mattock, as such treatment will deform the blade. In the 
field, split handles should be wrapped with a cord until they 
can be replaced by new handles. 

Canvas Buckets are used for watering animals, for washing 
carriages and equipment. Whenever possible, they should be 
dried before folding and replacing in the holders on the car- 
riages. 



242 FIELD ARTILLERY MATERIEL. 

A rip or hole may be patched and made practically water- 
tight by a coat of shellac. 

Lanterns are used for illuminating purposes in the field 
only. 

Paulins are used to cover the harness and guns when in 
the field or in park. On the march they are carried on the 
carriages, being folded to serve as seat cushions. Holes and 
tears should always be properly sewed, stitched or darned as 
soon as practicable. 

Picket Ropes are used in the field as drag ropes for the 
carriages or as picket lines for the animals. The ropes must 
be in a serviceable condition and free from knots. To keep 
them in a serviceable condition, splicing may often be neces- 
sary. 

CARE AND CLEANING OF THE DIFFERENT 
PARTS OF THE CARRIAGES. 

To disassemble and to clean the cylinder. — For cleaning, 
the cylinder is dismounted and emptied and the cylinder head, 
counter recoil buffer, and piston rod removed. The interior 
of the cylinder, the piston, the counter recoil buffer and 
the stuffing box should then be thoroughly cleaned by 
the use of cotton waste. The removal of the packing is 
not necessary in cleaning. The cylinder bore should be 
carefully inspected, and if any rust has formed it should be 
removed with coal oil, using if necessary, fine emery cloth. 
The latter must be used with great care to prevent any in- 
crease in the clearance between the piston and the cylinder. 
If rubbing, burring, or scoring of the parts is noted, the rough 
spots should be carefully smoothed down by a skilled work- 
man with a dead smooth file or with emery cloth, and the 
cause of the roughness ascertained and removed. Where 
unusual rubbing or scoring has occurred, the facts will be 
reported to the Officer of the Ordnance Department charged 



CARE AND PRESERVATION. 243 

with the duty of keeping the battery in repair, for his informa- 
tion and action. The exterior of the cylinder should be kept 
well oiled and free from rust and dirt, and an inspection made 
at least once a month to ascertain its condition. Where rust 
has formed it should be removed with coal oil, and, if neces- 
sary, emery cloth. For shipment or storage, or where the 
carriage is to stand without firing for extended periods, the 
cylinder should be coated with the light slushing oil used for 
the bore of guns. 

To fill the recoil cylinder. — If the cylinder is not com- 
pletely filled, loss of stability will occur and higher stresses 
than normal will be developed in the carriage. For this rea- 
son the cylinder should be filled with the greatest care, a 
commissioned should, himself, verify that the cylinder is full 
and that no air is left in it, exception of the void noted below. 
It is far easier to fill the cylinder when it is disassembled from 
the cradle. If assembled in the cradle, bring the gun to its 
maximum elevation and remove both filling and drain plugs. 
It is necessary that the drain plug holes should be lubricated 
on top of the cylinder. Fill through the hole in the piston 
rod. Allow a few minutes for the air to escape and the oil to 
settle. 

Re-fill and repeat two or three times. When satisfied 
that the cylinder is entirely full of oil, insert both plugs, and 
depress the gun to its maximum depression. After a few 
moments elevate again to its maximum elevation and unscrew 
both plugs. Now re-fill as described above. When entirely 
full, allow not more than two cubic inches (about one-fourth 
of a gill) of the oil to escape, insert both plugs and lash them 
with copper wire. It may happen that after firing a few 
rounds the gun will not return to battery. This may be due 
to, first, weakness of springs, second, stuffing box gland being 
screwed up too tight, or third, the oil having expanded, due 
to heat. It any case the cause must be ascertained and 



244 FIELD ARTILLERY MATERIEL. 

remedied, if due to expansion of oil, it is proven by the fact 
that the gun cannot be pushed into battery by force exerted 
on the breech of the gun. In that case elevate the gun to its 
maximum elevation and remove the filling plug. The oil 
will now escape permitting the gun to return to battery. In 
emergencies, water may be used in the cylinder. This should 
be done only when absolutely necessary, and never in freezing 
weather, and as soon as practicable the cylinder should be 
emptied, cleaned, and thoroughly dried and filled with hydro- 
line oil. About 9 pints of hydroline oil are required for filling 
the recoil cylinder. 

To empty the recoil cylinder. — The cylinder may be 
emptied either when assembled or disassembled from the 
cradle. In either case, remove both the filling and drain 
plugs, depress the forward end of the cylinder and drain the 
contents into a clean can or other receptacle over which a 
piece of linen or muslin has been stretched, for straining the 
oil. 

To clean the recoil cylinder oil. — The hydroline oil used 
in the cylinder should be cleaned and free from grit and dirt. 
The oil should be stored in the closed cans provided for the 
purpose, and be carefully protected from dirt, sand, or water. 
Oil withdrawn from the cylinders and containing any sedi- 
ment must not be used again until it has been allowed to 
settle for not less than 24 hours. When sediment has thus 
been permitted to settle great care must be taken not to 
disturb it in removing the oil. To insure the cleanliness of 
all cylinder oil it should be strained through a clean piece of 
linen or muslin before using. 

To clean the bore of the gun. — After firing and at other 
times when necessary, the bore of the gun should be cleaned 
to remove the residue of smokeless powder, and then oiled. 
In cleaning, wash the bore with a solution made by dissolving 



CARE AND PRESERVATION. 245 

one-half pound of Sal Soda in one gallon of boiling water. 
After washing with the soda solution, wipe perfectly dry and 
then oil the bore with a thin coating of the light slushing oil 
furnished for that purpose. Briefly stated, the care of the 
bore consists of removing the fouling resulting from firing, in 
obtaining a chemically clean surface and in coating this sur- 
face with a film of oil to prevent rusting. The fouling which 
results from firing of two two kinds — one, the production of 
combustion of powder, the other, copper scraped off the rota- 
ting band. Powder fouling because of its acid reaction, is 
highly corrosive, that is, it will induce rust and must be re- 
moved. Metal fouling of itself is unactive, but its presence 
prevents the action of cleaning agents. It should be removed 
if it accumulates At every opportunity in the intermission 
of fire, the bore of the gun should be cleaned and lubricated. 

To clean the breech mechanism. — The breech mechanism 
should be kept clean and well lubricated. It should be dis- 
mounted for examination and oiled when assembled. 

To cjean the recoil springs. — Dismount to clean. All 
rust should be removed and the springs well oiled before 
assembling. When the springs are dismounted the interior 
of the cradle should be cleaned and examined for defective 
riveting, missing rivet heads and scoring. The condition of 
the spring support guide should be noted and all burrs or 
scores carefully smoothed off. 

To clean, lubricate and care for the elevating and tra- 
versing mechanism. — The contact surfaces between the 
cradle and the rocker should be kept clean, thoroughly oiled, 
and free from rust. If indications of rusting, cutting, or 
scoring of these surfaces appear, the cradle should be dis- 
mounted, the rust removed, and rough spots smoothed away. 
The elevating and traversing mechanisms should be dis- 
mounted for thorough cleaning and overhauling. Thev 



246 FIELD ARTILLERY MATERIEL. 

should be kept well oiled and should work easily. If at any 
time either mechanism works harder than usual, it should be 
immediately overhauled and the cause discovered and re- 
moved. In traveling, the cradle should be locked to the 
trail by means of the elevating and traversing lock, so as to 
relieve the pointing mechanism of all travel stresses. 

To clean, lubricate and care for the wheels. — The wheel 
and wheel fastenings should be dismounted periodically and 
the fastenings, hub boxes, axle arms, and axle bore cleaned 
and examined. All roughness due to scoring or cutting should 
be smoothed off. The hollow part of the axle acts as a reser- 
voir for the oil to lubricate the wheel bearings. Experience 
will show how much oil is needed, but enough should be used 
to insure that the oil will pass through the axle arms to the 
hub caps. The nuts on the hub bolts should be tightened 
monthly during the first year of service and twice a year 
thereafter. The ends of the bolts should be lightly riveted 
over to prevent the nut from unscrewing. When the hub 
bolts are tightened, the hub band should be screwed up as 
tightly as possible against the lock washer at the outer end 
of the hub ring. 

GENERAL INSTRUCTIONS FOR THE CARE AND 
MAINTENANCE OF MATERIEL 

Assembling and Disassembling. 

(a) Cradle mechanism, cylinder, springs et cetera. 

All work upon recoil cylinders, sights, and other optical 
equipment should be done in the presence of a commissioned 
officer. The recoil cylinder should never be clamped in a vise, 
but when necessary to hold it from turning, a spanner applied 
to the front end of cylinder should be used. Never remove the 
cylinder end stud nut when the piece is at an elevation. See 
that proper kind of oil is used in cylinders and for lubrication. 



CARE AND PRESERVATION. 247 

Strain the oil used in rilling the cylinders through a fine clean 
cloth and be sure that the receptacles used in handling the 
oil are clean. Take every precaution to keep the interior of 
the cylinders clean and to prevent the entrance of foreign 
particles. In assembling the gland be sure that at least four 
threads of the gland are engaged with the threads of the cylin- 
der head. Lash parts with copper wire to prevent unscrew- 
ing. Close down the ends of the recoil-indicator guide to 
avoid loss of the indicator. Prevent possible injury to can- 
noneers by causing them to stand clear of the counter-recoil 
spring column in assembling or dismounting. Remove cylin- 
der end stud screw before trying to unscrew cylinder end stud. 

(b) Gun 

In moving the gun on or off the cradle, provide ample 
support for the breech end, so that the gun clips are in pro- 
longation of the cradle guides; if this is not done the cradle 
guides may be ruined. 

(c) Elevating and traversing mechanism. 

If the gun will not remain at the elevation at which 
set, the crank shafts are probably not correctly assembled. 
If the elevating screw do not house in traveling, they are in- 
correctly assembled. 

(d) Sights and quadrant. 

Frequently verify the adjustments of sights and quadrant. 
Require special care in handling sights. Do not permit can- 
noneers to use front sight as a handle in mounting. Be sure 
that the range disk of the quadrant and range strip of the rear 
sight shank are graduated for the particular type of ammuni- 
tion used by the battery. This also applies to the fuze setter. 

Care of Materiel, 
(a) Parts of the Carriages. 

All nuts are secured by split pins, which should be replaced 
and properly opened when nuts are screwed home. Do not 



248 FIELD ARTILLERY MATERIEL. 

strike any metal part directly with a hammer; interpose a 
buffer of wood or copper. All working and bearing surfaces of 
the carriage require oiling; those not directly accessible for this 
purpose are provided with oil holes closed by spring covers or 
handy oilers. Do not permit brake levers to be released with a 
kick or blow. It has been found that the apron hinges oc- 
casionally become broken, and that the apron hinge pins are 
frequently lost. Whenever this happens the hinge or hinge- 
pins should be immediately replaced. For if this is not done 
the apron, which is very expensive is apt to become cracked 
or broken. When the lunette becomes loosened the lunette 
nuts should at once be tightened. 

(b) Wheels. 

Keep hub bolts and hub bands properly tightened. To 
tighten the hub bands screw them as tightly as possible with a 
wrench and then force them farther by striking the end of the 
wrench with a hammer. All wheels and pintle bearings 
should be frequently oiled. 

(c) Inspections. 

Battery commander should frequently make a detailed 
inspection of all the vehicles in the battery, to see if any parts 
of them are broken or if any screws, nuts, split-pins, et cetera 
are missing. If any such defects are found they should im- 
mediately take steps to replace missing or broken parts. At 
these inspections the material should also be examined to 
ascertain whether the cleaning schedules have been properly 
carried out. Compliance with these instructions will do much 
toward prolonging the life of the carriage. 

Firing, Precautions and Preparations for. 

Before firing, inspect to see that cylinders are properly 
closed and that the cylinder end stud nut and piston rod-nut 
are in place. If time permits, oil slides before firing. Note 



CARE AND PRESERVATION. 249 

length of recoil for the first few shots to be sure that the recoil 
mechanism is working properly. There is no danger as long 
as the recoil does not exceed 48 inches. Therefore, for first 
shot always set recoil indicator for about 42 inches. If the 
gun fails to return fully into battery, it is probably due (1) 
to dirt on slides and guides, (2) to cutting of slide surfaces on 
account of lack of oil, (3) to gland being screwed up too tightly, 
(4) to dirt or foreign particles in the cylinder, and especially 
in the counter recoil buffer recess, (5) to weakness of springs, 
90% of such cases will be found to be due to 1, 2 or 3. Lock 
the cradle to the trail at drill and at traveling to avoid unneces- 
sary strain upon the pointing mechanism. After unlimbering, 
release elevating and traversing lock before attempting to 
elevate or traverse gun. 

Cleaning and Care of Leather. 

All leather contains more or less oil. When the amount of 
oil decreases the leather becomes harder, less pliable, and 
shows a tendency to crack. It loses its elasticity and breaks 
more readily under sudden strains. Exposure to the sun 
evaporates the oil and exposure to the rain washes it out, 
both conditions tending in the long run to bring the same 
result, namely, hardening and stiffening of the leather. Ac- 
cumulations of foreign substances are very injurious for they 
tend to absorb the oil from the leather underneath, leaving it 
dry and hard, or they retain moisture on the surface, prevent 
the air from getting to it and rot the leather. Also many sub- 
stances such as perspiration and excretion from the horse 
contain chemicals which are very injurious. For these rea- 
sons all leather must be kept clean. The cleaning agent 
used is castile soap with water. All pieces should be taken 
apart and as much dirt and dust as possible removed with a 
damp sponge or cloth. All remaining dirt is then removed by 
washing with castile soap and water. In doing this always 



250 FIELD ARTILLERY MATERIEL. 

use as little water as possible. Wring the sponge out nearly 
dry, rub it on the soap and work it with the hands until a 
thick, creamy lather is formed. Then scrub the leather 
thoroughly until all dirt is removed. Special care should 
be taken around spots that have been in contact with meta 
perspiration or excreta. If there is an old accumulation of 
dirt a soft stick may be used to scrape this off. Never allow 
a knife or a piece of glass to be used or any sharp edged instru- 
ment. After all dirt is removed run the sponge in one direc- 
tion, all the way along the leather to remove all remaining 
dirt and extra lather. Never allow the pieces to be rinsed 
off in a bucket of water. Metal parts should be washed 
thoroughly and dried and if necessary any rust removed with 
a crocus cloth. Although as little water as possible is used 
some of the oil in the leather will certainly be washed out, and, 
to keep the leather in proper condition, it must be replaced. 
After an ordinary cleaning this is normally done by an applica- 
tion of saddle soap. Saddle soap is not a cleaning agent — 
only a dressing for leather. It contains enough oil to replace, 
if properly applied, all loss through ordinary use. It is used in 
the same manner as castile soap, in the form of a thick, creamy 
lather, rubbed well into the leather and allowed to dry. 
The leather should be well rubbed with the hands while drying, 
to keep it soft and pliable, and to work the oil in. Always 
allow it to dry in the shade, preferably for several hours, and 
never assemble pieces, especially fastening straps into buckles 
until thoroughly dry. Oil is never applied directly to leather 
unless it has become so hard and dry that saddle soap is not 
sufficient to soften it. There is only one oil issued for that pur- 
pose. That is "Neat's Foot Oil." This should only be applied 
to the flesh side of the leather and very lightly. Several light 
applications give much better results than a few heavy ones. 
The oil should be well rubbed in with the hands and should be 
preferably applied after cleaning the leather with castile soap 



CARE AND PRESERVATION. 251 

and water, as the pores of the leather are then more open and 
the oil penetrates much better. Never oil leather until it 
becomes greasy, for, besides wasteful, it makes the leather 
too spongy. In emergencies, where Neat's Foot Oil cannot 
be procured any good vegetable oil may be used, preferably 
olive oil. This is only for emergencies and is not to be used 
unless Neat's Foot Oil or saddle soap cannot be had. All 
new leather equipment should be cleaned with castile soap and 
water as soon as unpacked as leather very often becomes cov- 
ered with mold after being packed in boxes for some time. 
Ordnance leather as it comes to the battery is very dry and 
should be thoroughly oiled before being used. New equip- 
ment after being washed thoroughly, should be given, in sev- 
eral light applications as much oil as it will absorb without 
becoming greasy. Each application should be allowed to dry 
thoroughly and should be given frequent rubbings to soften 
the leather. With the proper kind of preparation for use there 
is no excuse for the large amount of broken new leather equip- 
ment which is so common. In packing harness for shipment, 
especially into harness sacks the harness should be cleaned 
and oiled and then dried for at least twenty-four hours before 
putting into the sacks. After removing from the sacks at the 
destination, cleaning and dressing with saddle soap is sufficient. 
When the leather is dirty, clean it — not to improve its looks 
but to preserve it. When wet allow it to dry in a warm (not 
hot) place, in cold weather; or in the shade in summer. When 
it is dry apply saddle soap or oil. Never hang any piece of 
equipment over a nail or sharp edge as cracks always develop 
where the leather has been folded over sharply. Ordinary 
oils and greases rot leather, so all such equipment must be 
kept away from contact with them. Never leave any piece 
of leather where it will chafe against any sharp edge or corner 
and never leave it exposed to the sun longer than necessary. 



252 FIELD ARTILLERY MATERIEL. 



Care of Cloth Equipment. 

All cloth equipment should be kept as clean as pos- 
sible by continual brushing. The fewer times necessary to 
wash it, the longer its life. Canvas goods such as paulins, 
webbing, etc., when it becomes necessary to wash them 
should be scrubbed with Paco, or H. & H. soap and water. 
Make a solution of one cake of either soap in nine cups of hot 
water. Brush the article to be cleaned thoroughly and spread 
it on a clean table. Scrub with the above solution and scrub- 
bing brush until a good lather appears. Rinse in clean water 
and hang in the shade to dry. Woolen articles may be 
cleaned in the same manner or with ordinary laundry soap. 
The first method being always the best. It is preferable to 
wash these in cool or warm water, as hot water shrinks them. 
Never wring woolens out, but after washing, rinse in clean 
water and hang immediately up to dry. Saddle blankets 
should be kept well brushed and should be frequently un- 
folded, hung in the sun and beaten with a whip. When re- 
moved from the horse they should be doubled over with the 
wet side out and put in the shade to dry. If no shade is avail- 
able, and they must be exposed to the sun, always fold the wet 
side inward. With these precautions, saddle blankets should 
not need washing oftener than twice a year. In washing 
immerse the blanket in tepid soap suds repeatedly until clean, 
rinse in clean water, and hang in the sun to dry. Do not 
scrub the blanket. 

Care of Metal. 

All metal equipment should be kept clean and free from 
rust. Coal oil is used to remove rust, but it must always be 
removed as it will rust the metal if allowed to remain. The 
coal oil should be applied to the metal and if possible allowed 
to remain for a short time. This will loosen and partially dis- 



CARE AND PRESERVATION. 253 

solve the rust so that it can be rubbed off with a rag or a sponge. 
Continued applications may be necessary if there is much 
rust. A solution of Sal Soda is also a good rust remover. 
The articles must be washed thoroughly after using this to 
remove all traces of the soda as it is a very active corrosive. 
Never scour metals to remove rust if it can be avoided as this 
leaves a roughened surface which will rust again much more 
easily. Polished surfaces such as brass fittings should be 
cleaned and polished with Lavaline. This may also be used 
on the bearing surfaces of steel collars. All surfaces after 
cleaning should be dried thoroughly and if not painted should 
be greased with cosmis or cosmoline. These form an air- 
proof coating over the metal surface so that no moisture may 
reach it and cause rusting. If the metal is not dried thorough- 
ly, some moisture may be held between the grease and the 
metal surface which will in time cause rust to appear. Care 
must be taken that the grease covers the surface completely. 
All surfaces against which there is no friction should be 
painted and kept so. Ordinary olive drab or collar paint is 
very satisfactory for this purpose. 

Care of Guns During and After Firing. 

Always while firing keep the bore as clean as possible. 
If there is time to swab out between shots, do so. During 
continued firing a bucket of water should be kept near the gun, 
and the sponge on the rammers staff kept wet while swabbing. 
Watch the recoil indicator and occasionally push it ahead so as 
to be sure you are getting a correct reading. Be sure that the 
gun returns fully into battery after each shot. Keep the am- 
munition, and especially the rotating bands, free from dust 
and dirt. 

The rotating band should be greased very lightly with 
cosmis just before inserting the projectile into the 
breech. In continued firing, oil the slides frequently. Keep 



254 FIELD ARTILLERY MATERIEL. 

the fuze setter clean and be careful that no dirt gets down 
around the stop pin. Examine the breech recess frequently 
and wipe out all dirt and brass filing that may accumulate. 
The gun should be cleaned thoroughly immediately after 
firing. Make a solution of one pound of sal soda in one 
gallon of boiling water. Remove the breechblock and carrier, 
and let one man clean and oil it thoroughly while the rest of the 
gun is being cleaned. Remove the sponge from the rammer 
staff, and over the brass rammer, fit a piece of folded burlap. 
Fold this burlap as many times as you can and still force it 
through the bore. Soak the burlap in the sal soda solution and 
swab the bore out thoroughly. Be careful to remove all 
copper filing, and the bore should be as bright as a piece of 
glass when finished. After cleaning it is best though not 
absolutely necessary to swab out with clean water. Then dry 
thoroughly with a dry swab, and grease every exposed surface. 
In cleaning the breechblock and firing mechanism always dis- 
mantle it completely. Clean and oil the slides, fuze setters 
and all parts of the carriage. Decap the empty cartridge 
cases and wash them out thoroughly with the sal soda solu- 
tion. There is a decapping set with every battery. Rinse 
out in clean water and set them in the sun to dry. 

A CLEANING SCHEDULE FOR MATERIEL. 
Daily. 
Before leaving the park: 

1. Unlock boxes and chests and secure them with snaps. 

2. See that all tools, paulins, etc., are secure. 

After returning to the park: 

1. Remove from carriages all dust, excess oil and mud. 
Examine for missing nuts, split pins, broken parts and parts 
that need adjustment. Make necessary repairs. 



CARE AND PRESERVATION. 255 

2. Clean and oil breech recess and breechblock; after 
firing, clean bore with salsoda solution, wipe perfectly dry 
and oil. 

3. Oil wheels, elevating and traversing mechanism, 
tools if necessary. 

4. See that all oil holes are properly closed and that car- 
riages are ready for immediate use. 

5. Clean and oil without dismounting; rear sight, quad- 
rant and fuze setter. 

6. Lock all boxes and chests. 

7. Signal detail: clean all instruments, oil all exposed 
bearing surfaces. Test telephones and go over all wire used 
that day and repair same by covering exposed parts. Have 
all instruments, wire etc., ready for immediate use. 

8. Clean all collars and bits and dry the blankets; wipe 
dirt from the harness. 

9. Clean and oil all pistols and revolvers that have been 
used that day. 

Weekly. 

1. Wash and clean entire carriage. 

2. Disassemble and clear all oil breech mechanism. 
Always do so immediately after firing. 

3. Clean out and fill with oil, all oil holes of gun clips and 
cradle pintle. 

4. Clean all leather straps as you would clean harness. 

5. Take apart and thoroughly clean all parts of harness. 

6. Take apart and clean and oil all pistols and revolvers. 

7. Clean with castile soap and harness soap all leather 
of the personal equipment. 

Monthly. 

1. Disassemble the following and clean and oil: elevat- 
ing mechanism, traversing mechanism. 



256 FIELD ARTILLERY MATERIEL. 

2. Pull from battery and clean 'and oil guide rails and 
clips. Trip gun and test recoil. 

3. Tighten all hub nuts and inspect wheels for dish. 

4. Take off wheels, clean and oil axles and hubs. Re- 
place hub liner when necessary. 

5. Dismount poles, double trees and spare pole, clean 
and oil. 

6. Dismount rear sight bracket from support, clean and 
oil. Do the same for the front sight. 

Every Three Months. 

1. Dismount, clean, oil and assemble the recoil mechan- 
ism. 

2. Inspect the surplus kits and replace all articles that 
are not in proper condition. 

3. Unpack, clean, oil and repack the battery and store 
wagons, forge limber. 

Every Six Months. 

1. Inspect all articles of the permanent camp equipment, 
dry, oil and repair when needed. Pitch tentage for examina- 
tion and drying. 

2. Examine all articles in store such as leather, harness 
and spare metal parts. Clean the harness, dub the leather, 
oil all metal parts. 

PRECAUTIONS AND GENERAL INSTRUCTIONS. 

1. Never allow steel parts to be struck with a steel 
hammer. Always use a copper drift between the hammer and 
the steel part. 

2. Never try to force a delicate part if stuck. The 
sticking is probably due to rust and the parts can be loosened 
by soaking in coal oil or by heating the exterior surfaces with 
a torch. 



CARE AND PRESERVATION. 257 

3. Be careful in using screw drivers or wrenches not 
to let them slip and thus ruin the heads of the screw or nut. 

4. Insist upon the rule that any part needing repairs 
be repaired immediately upon arrival in garrison or camp. 

5. Never allow a broken part to be stored except for the 
action of an inspector or survey. 

6. Before any article is put away for storage, have it 
thoroughly inspected and make necessary repairs. 

7. See that all articles of your equipment are always 
marked or stamped with the insignia and the battery number. 

8. Hold all members of your organization responsible 
for any carelessness or negligence in the care of the equip- 
ment. 



T B— 17 



258 FIELD ARTILLERY MATERIEL. 



CHAPTER XIV 
FIRE CONTROL EQUIPMENT. 

SIGHTS. 

The instruments provided for sighting and laying the gun 
include a line sight, a rear sight, a front sight, a panoramic 
sight, and a range quadrant. 

Line sights. — The line sight consists of a conical point 
as a front sight and a V notch as a rear sight, located on the 
top element of the gun. They determine a line of sight parallel 
to the axis of the bore, useful in giving general direction to the 
gun. 

Front and rear sights.— The front and rear sights are for 
general use in direct aiming. The front sight carries cross 
wires. The rear sight is of the peep variety, constructed as 
follows: To the sight bracket is attached the shank socket 
upon which a spirit level is mounted for the necessary correc- 
tion due to difference in level of wheels. The sight shank con- 
sists of a steel arc, the center of which is the front sight. It 
slides up and down in the shank socket and is operated by a 
scroll gear. A range strip is attached to the face of the shank 
and is graduated up to 6500 yards, least reading 50 yards. 
To the left side of the shank is an elevation spirit level, per- 
mitting approximate quadrant elevations to be given with 
the sight shank when the quadrant is out of order. 

The peep sight and its deflection scale are mounted above 
the shank. This peep traverses along a screw operated by a 
knurled head. A socket and ratchet are also provided for 
the attachment of the panoramic sight. 



260 FIELD ARTILLERY MATERIEL. 



Nomenclature of the important parts of the Rear Sight:— 

Peep sight Shank socket 

Elevation level Cross level 

Deflection scale Leveling screw 

Peep sight screw and head Scroll gear and handle 

Range strip Rear sight bracket 

Shank Panoramic sight socket and rat- 
chet 



PANORAMIC SIGHT, MODEL 1017. 
Description. 
The panoramic sight is a vertical telescope so fitted with 
an optical system of reflecting prisms and lenses that the 
gunner can bring into his field any point in a plane perpendicu- 
lar to the axis of the telescope. The optical characteristics 
of the instruments are as follows: 
Power=4. 
Field of view=10°. 

The rotating head prism has a movement of 600 mils in a 
vertical plane; movement is obtained by turning elevation 
micrometer. The amount and direction of rotation is indi- 
cated on a scale in the head by the elevation index and mi- 
crometer. The scale is graduated in 100-mil intervals, the 
micrometer in mils. One complete turn of the micrometer 
is equivalent to one space on the sale. The head is level when 
the index is opposite 3 and micrometer at zero. 

Movement in azimuth is obtained by turning azimuth 
worm. The amount of rotation is read from the scale on the 
azimuth circle and the azimuth micrometer. The azimuth 
micrometer may be turned independently of the azimuth worm 
to set any desired deflection. Figures in black are for right- 
hand deflection and in red for left-hand deflection. The scale 
on the azimuth circle is graduated in 100-mil divisions from 
to 32 in each half circle. The micrometer is graduated for 



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ft^ > m H 




@ © 



262 FIELD ARTILLERY MATERIEL 

every mil. For larger angular deflections, by turning the 
throw-out lever the azimuth worm is disengaged, permitting 
the head to be turned to any desired position. 

The reticule is provided with a horizontal and a vertical 
cross line. The horizontal line is graduated in mils. 

An open sight attached to the side of the rotating head is 
for approximate setting of the instrument. 

No disassembling or adjustment of the panoramic sight, 
except as described herein, is to be made, except by ordnance 
personnel detailed for such work. 

The panoramic sight is seated in a T slot in a socket of the 
sight, model of 1916, in firing, and is carried in a panoramic 
sight case on the shield when traveling. 

Use of the Panoramic Sight for Direct Fire. 

Level rocker with zero on range scale opposite 300 on 
angle-of-site scale and gun at center of traverse. Set azimuth 
scale at zero, azimuth micrometer knob at zero, micrometer 
index at zero, elevation scale at 3, and elevation micrometer 
knob at zero. By means of cross-leveling knob on sight 
socket bring cross-level bubble level. 

Correct for deflection in azimuth by turning azimuth 
micrometer until required deflection is opposite fixed arrow 
pointer; bring zero on micrometer index to zero on azimuth 
micrometer by means of micrometer-index knob. 

Elevate gun by means of angle-of-site handwheel and 
traverse until cross hairs of panoramic sight are on target. 

For Indirect Fire. 

Level rocker and set scales for zero setting as directed in 
first paragraph under "direct fire." 

Lay off required deflection in azimuth by means of mi- 
crometer index and azimuth worm knob, so that deflection may 



FIRE CONTROL EQUIPMENT. 263 

be read from azimuth index and azimuth micrometer. Trav- 
erse gun until vertical cross hair of panoramic sight is on aim- 
ing point. 

Vertical angles may be read by means of elevation scale 
and micrometer scale. Zero point of elevation scale is 3. 
Each division on elevation scale represents 100 mils. 

All scales are graduated in mils. 

The open sight on side of rotating head is used to ob- 
tain preliminary direction of sight. 

In turning azimuth angles greater than 100 mils the throw- 
out lever may be pressed and rotating head turned to nearest 
division in even hundreds desired. Each unit on azimuth 
scale represents 100 mils. 

Panoramic Sight, Model of 1915. 

The panoramic sight is a vertical telescope so fitted with 
an optical system of reflecting prisms and lenses that the gun- 
ner with his eye at the fixed eyepiece in a horizontal position 
can bring into the field of view an object situated at any point 
in a plane perpendicular to the axis of the telescope. 

The rays coming from the object are reflected downward 
from the rotating head prism into the rotating prism. The 
rotating prism rectifies the rays ; after their passage through the 
achromatic objective lens, the lower reflecting prism reflects 
them in such a way that there is presented to the eyepiece a 
rectified image, which the eyepiece magnifies. A glass reticule 
marked with graduated cross lines is located in the focal plane 
of the instrument, with the intersection of the cross lines co- 
incident. 

The instrument has a universal focus, a magnifying power 
of 4 and field of view of 180 mils. 

The principal parts of the panoramic sight are the rotat- 
ing head, the elevation device and its micrometer, the azi- 
muth mechanism with limb and micrometer, the rotating prism 



FIRE CONTROL EQUIPMENT. 265 

mechanism, the deflection mechanism, R and L scale and mi- 
crometer, the shank and the eyepiece. 

The limb or azimuth scale is divided into 64 parts, each 
division representing 100 mils. 

The azimuth micrometer is divided in 100 equal divisions 
or mils, numbered every 5 mils. One complete revolution of 
the azimuth micrometer is equal to the distance between di- 
visions on the azimuth scale. The limb of the deflection scale 
is divided into six divisions; three on each side of the zero, red 
for right and black for left, each division representing 100 mils. 
The deflection micrometer, engraved upon the front end, is 
graduated into 100 equal divisions, numbered every 10 mils, 
red and black in opposite directions. 

THE RANGE QUADRANT 

The range quadrant consists of the quadrant spring fasten- 
ing and bracket, rocker, body, scroll gear, range disk, range 
and cross levels with suitable leveling screws, and a microm- 
eter to set off the angle of site. 

The range disk is graduated to 6500 yards, least reading 
every 50 yards, scale numbered every 500 yards. This disk 
is operated by a scroll gear. Large changes in range may be 
made by pulling out the hand-wheel, thus disengaging the 
scroll gear, and moving the body and index to the approxi- 
mate range, whereupon the hand-wheel is released, and the 
range accurately set by again turning the hand-wheel. 

The micrometer has 100 divisions and is operated by a 
milled head. The limb of the micrometer, called the level 
scale, is graduated from 2 to 5, each division corresponding to 
one complete revolution of the micrometer. The arbitrary 
reference point or mean position of the level holder is 300 which 
corresponds to a point on the same level as the gun. 



FIRE CONTROL EQUIPMENT. 267 



CARE AND INSPECTION OF SIGHTS. 

Rear sight Bracket. — Should not be bent, broken or 
cracked. Must be seated firmly in the bracket support. 

Shank Socket Mechanism. — Not bent or burred ; interior 
of shank socket, scroll and worm gears free of scratches, burrs 
or deformed threads. Sight shank easily inserted and moved 
up and down in the socket. Scroll gear securely held in mesh 
with rack of sight shank. For large movements of shank, 
should be easily disengaged by pulling out scroll gear handle; 
must be securely held in place by spring when released. Keep 
interior well lubricated. See that level vials of cross and eleva- 
tion levels are intact and bubbles not too large. 

Sight Shank. — Rack on right side must engage with scroll 
gear; keep lightly oiled. Sight shank should remain in fixed 
position except when disengaged or operated by scroll gear 
handles. For changes in range of 300 yards or less use only 
the scroll gear; over 300 yards pull scroll gear handle and slide 
shank up or down in socket by hand, making accurate setting 
with the scroll gear. 

Panoramic Sight. — Lug must fit snugly in T slot of rear 
sight and then held fast by clamp screw and ratchet. When 
making ready for march order, first set the azimuth and R & L 
deflection scales at zero, and the elevation scale at 300. Re- 
lease clamp screw and ratchet. In removing panoramic sight, 
grasp at center below the azimuth gear case, lift vertically 
out of the socket, lower the top of sight to the left and replace 
in panoramic sight box. 

Quadrant. — Must fit snugly in its bracket, spring catch 
engaging. Nut on range disk must be tight to prevent slip- 
ping. To remove quadrant, press on spring catch before 
sliding off bracket. 



268 FIELD ARTILLERY MATERIEL. 

The sights are correctly adjusted when, at zero elevation 
and deflection, correction having also been made for difference 
of level of wheels, the line of sight is parallel to the axis of the 
bore. 

The range quadrant is correctly adjusted when, with the 
range disk set at zero, level set at 300, axis of gun horizontal 
and corrected for difference of level of wheels, the bubble of 
the range level is centered. 

In adjusting sights, the panoramic sight should first be 
corrected. If the rear sight is adjusted first, it will require 
readjustment if the subsequent adjustment of the panoramic 
sight causes a change in position of the rear-sight range strip. 

To adjust the panoramic sight. — Select a well defined 
point at least 2000 yards distant. If the bore sights are not 
available, stretch two threads or hairs from the tail of a horse 
across the grooves marked on the face of the muzzle and fas- 
ten them by a strap or rubber band. Remove the firing-lock 
case from the hub of the block-carrier. By sighting through 
the hole in the vent bushing of the breech-block, adjust the 
intersection of the cross hairs on the distant point, using the 
elevating and traversing mechanisms of the gun. Now with- 
out moving the gun or disturbing the laying of the cross hairs, 
bring the cross wires of the panoramic sight on the same dis- 
tant point by means of the azimuth scale worm-knob and the 
scroll gear of the rear sight {on panoramic sights, M1915, to 
the deflection R & L scale should first be made to read 0, and the 
elevation scale of the objective to read 300). The cross hairs of 
the gun and the cross wires of the panoramic sight will thus be 
laid on the same point. Now adjust the azimuth micrometer 
scale to read by means of unscrewing and tightening the 
screw on the milled head. Loosen the nut on the range strip; 
move it up or down until it reads (0) 100. Tighten the nut 
again. Verify the laying. For this adjustment, it is not 



FIRE CONTROL EQUIPMENT. 269 

necessary to have the wheels or the carriage on a level plat- 
form; cross level should be leveled. 

To adjust the rear sight. — Having adjusted the panoramic 
sight and the rear sight range strip as described above, and 
without disturbing the laying of the gun, shift the deflection 
scale of the peep sight and raise or lower the front sight until 
the cross wires of the latter are laid upon the same distant 
point. Now loosen the two screws of the deflection scale and 
place the of this scale opposite the index of the peep sight. 
The front sight is raised or lowered by removing the split 
pins and then turning the front sight in the sight bracket sleeve 
either up or down. 

To adjust the quadrant.— (a) If an adjusted B. C. tele- 
scope or another gun with its quadrant in proper adjustment 
is available, the angle of site of some distinctly visible and dis- 
tant point is measured by either of these means. The gun to 
be adjusted is then laid upon this distant point either with the 
bore sights, or with the tangent sight set at (or some other 
convenient) range. The measured angle of site is then set off 
on the level scale of the quadrant and the bubble of the range 
level is centered by turning the hand-wheel of the range disk. 
By using the quadrant wrench, the range disk is then adjusted 
to read range, (or the convenient range previously set off on 
the tangent sight). 

(b) If no means are at hand to correctly measure the 
angle of site of a distant point, the quadrants may be adjusted 
by using two guns as follows: Unlimber two guns at about 
the same level, first seeing that the sights are in adjustment 
(par. 75). Lay both guns upon some distant point by means 
of the panoramic sight set at range. Now set both quad- 
rants for the same angle of site (roughtly estimated A. S. of 
the distant point) and center the bubbles of the range level by 
turning the hand-wheel of the range disks. By means of 



270 FIELD ARTILLERY MATERIEL. 

the quadrant wrench, adjust the range disk of one o£ the 
quadrants to agree with the other. Whatever error exists 
will now be the same in each quadrant. 

Now move one of the guns about 100 yards away and turn 
the muzzles toward each other. With the sights set at 
range, lay the panoramic sights upon each other and measure 
the angle of site of each gun. Half the difference of the two 
readings will be the slope of the line of sight between the two 
guns. On the level scale of the quadrant which read the greater 
angle of site, set off 300 plus the half -difference, on the 
other quadrant set off 300 minus the half-difference. Now 
center the bubble of the range level by turning the hand-wheel 
of the range disk. By using the quadrant wrench, adjust the 
range disk until it reads range. Having thus adjusted two 
guns, the others may be adjusted by the first means described. 

OBSERVING INSTRUMENTS. 
B. C. Telescope, M. 1915. 

The B. C. Telescope, M. 1915, is a binocular observing 
instrument of the scissors type. The two tubes of the tele- 
scope may be clamped either in a vertical or a horizontal posi- 
tion. In the former position the objectives are 12 inches above 
the eyes of the observer, and in the latter position they are 
24 inches apart and at the same height as the eyes of the ob- 
server. In both cases they permit the observer to take ad- 
vantage of some shield or other cover and still obtain a full 
view of the sector of observation. The tubes may be adjusted 
for the observer's interpupillary distance in either the vertical 
or the horizontal position. The eyepieces may be adjusted to 
the eyes of the observer by screwing in or out. 

The principal parts of the telescope are : — Leveling mech- 
anism, azimuth mechanism, elevating mechanism, angle of 
site mechanism, the telescopes and the tripod, A carrying 



272 FIELD ARTILLERY MATERIEL. 

case is provided separately for the instrument and for the tri- 
pod. In garrison a storage case is also provided. 

The leveling mechanism consists of a ball and socket joint 
operated by the vertical spindle clamping screw. 

The azimuth mechanism consists of the azimuth worm 
knob with its lever, operating the azimuth worm and worm 
wheel; the adjusting or slow motion knob and the azimuth 
clamp. The azimuth limb is divided into 64 parts, each 
division representing 100 mils. The azimuth micrometer is 
divided into 100 equal parts or mils, numbered every 10 mils. 
One complete revolution of the micrometer is equal to one di- 
vision of the limb. The scales therefore correspond to those 
on the panoramic sight, 6400 mils to the circumference. 

The leveling mechanism is operated by the small elevation 
worm knob. 

The angle of site mechanism consists of the level, the angle 
of site scale and micrometer with its worm knob. 

The telescopes consist of the eyepieces, telescopic tubes 
with their optical systems. In the right eyepiece is a grad- 
uated cross wire which can be rotated for either the horizon- 
tal or the vertical position. 

The tripod is similar to the usual telescopic instrument 
tripod. 

The optical characteristics of the instrument are as fol- 
lows: — Power 10; field of view 75 mils; focal length of objec- 
tives 11| inches; the field is flat, free from chromatic and 
sphercial aberration, coma and distortion. 

Care and Instructions. 

To set up the tesescope. — First set up the tripod, clamping 
and propping the legs so as to obtain the desired cover and 
view. By means of the vertical spindle clamping lever, ap- 
proximately center level on azimuth worm case and clamp 
tightly. Carefully take out B. C. telescope from case and 



FIRE CONTROL EQUIPMENT. 273 

while pressing on locker plunger, place telescope on vertical 
spindle so that the projection on the azimuth worm case 
will fit into the corresponding slotted segment of the telescope. 
Release the locking plunger. 

To focus the eye pieces, — Adjust each eye piece separately 
by turning the same until the image of a distant object ap- 
pears sharply defined. Read the diopter scale, plus or minus, 
and note for future use. 

To adjust the interpupillary distance. — The eye pieces 
having been focussed, loosen the large friction clamp knob in 
front. Grasp both tubes with the hands and separate or close 
them in (either in the vertical or horizontal position) until 
the fields of view of the two eye pieces are exactly coincident 
and present a single image to the eyes. This can be tested by 
alternately closing one eye and then the other, noting any 
movement in the image. Tighten the large friction clamp 
knob. Read the interpupillary scale and note for future use. 

To lay on any point. — Level the instrument by means of 
the vertical spindle clamping screw. Bubble must remain ap- 
proximately centered while instrument is turned 1600 mils. 
Set both the azimuth index and the micrometer to read zero. 
Release the azimuth clamp shaft knob; turn the telescope 
toward the- point and tighten the azimuth clamp shaft knob. 
Bring the vertical wire accurately on the point by turning the 
azimuth adjusting worm knob. 

To measure the deflection and site of a target. — Lay the 

zero on the aiming point as above. If the line of sight must be 
moved through a large angle, press down the azimuth worm 
lever as far as it will go and while holding it down move the 
azimuth mechanism until the line of sight is approximately 
directed upon the target ; then release the worm lever and bring 
the cross wires accurately on the target by turning the azimuth 
worm knob (for deflection) and the elevation worm knob (for 



274 FIELD ARTILLERY MATERIEL. 

elevation). Center the site level. Read the deflection 
and site. 

For carrying the B. C. telescope assembled on the tripod, 
clamp tightly the vertical spindle clamping lever ; close in and 
clamp the tubes of the telescope ; slide up and clamp the lower 
tripod legs ; then carry the telescope over the shoulder by grasp- 
ing the tripod legs, tube bases of telescope resting on the 
shoulder. 

To dismount the B. C. Telescope and to pack in carrying 
case. — Screw in both eye pieces. Press on the locking plunger 
and lift the telescope vertically off the spindle. Unclamp the 
large friction clamp knob, bringing the tubes together and 
insert in the carrying case; close and lock the lid. In dis- 
mounting the tripod the leg separators of the upper sections 
should first be undamped. After the lower legs have been 
assembled, they should be clamped. To set up the tripod the 
operation is reversed. 

Aiming Circle, M, 1916. 

The Aiming Circle is an angle measuring instrument only 
and consists of a telescope, leveling mechanism, angle of site 
device, elevating mechanism, azimuth circle and compass, 
mounted on a tripod. 

Its leveling, azimuth and angle of site mechanisms are 
similar to those in the B. C. Telescope, as is also the tripod. 
The elevating mechanism consists of elevating worm knob 
and gear connecting it with the telescope. The telescope has 
a universal focus, magnifying power of 4, and a field of 180 
mils. The cross wires are illuminated by a window. The 
compass is secured by the needle release button. 

Care and Instructions. 

Glass compass cover should fit tightly. Compass needle 
when clamped should not rotate while instrument is revolved 



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276 FIELD ARTILLERY MATERIEL. 

or tipped. When release button is pressed, compass must 
swing freely on pivot and again remain clamped when button 
is released. Compass should be released only when aiming 
circle is set up and horiontal. 

Bubble must remain approximately centered while instru- 
ment is turned 1600 mils. 

To lay on any point. — Set both the azimuth index and 
the micrometer to read zero. Release the wing nut; turn the 
telescope toward the point and again tighten the wing nut. 
Bring the vertical wire accurately on the point by turning the 
adjusting worm wheel. 

To measure the deflection and site of a target. — Lay 

on the aiming point as above. If the line of sight must be 
moved through a large angle, press down on the azimuth worm 
lever as far as it will go and while holding it down, move the 
azimuth mechanism until the line of sight is approximately 
directed upon the target; then release the worm knob (for 
deflection) and the elevation worm knob (for elevation). 
Center the site level. Read the deflection and site. 

To measure the compass deflection of a target. — Set 

both the azimuth index micrometer to read 40. Release the 
wing nut ; turn the teslecope until the N and S poles of the com- 
pass are respectively near the N and S points marked on the 
compass box. Make the coincidence accurately with the ad- 
justing worm wheel. Now proceed to measure the deflection 
and site of the target as described above. 

The Tripod and Azimuth Gear Case. — The leather cover 
protecting the ball and socket joint must fit snugly both above 
and below, and be free of rips or holes. The ball and socket 
joint and the tripod legs should be easily adjusted and moved, 
but should remain fixed when clamped by the clamping levers. 

For carrying the aiming circle assembled on the tripod, 
the wing nut and the vertical spindle clamping lever should be 



FIRE CONTROL EQUIPMENT. 277 

clamped tightly and the instrument carried over the shoulder 
by grasping the tripod legs, head of tripod resting on the 
shoulder. 



Adjustments B. C. Telescope and Aiming Circle. 

The B. T. Telescope and the Aiming Circle are correctly 
adjusted when the following conditions prevail: Telescope 
properly focussed ; plane of level perpendicular to the vertical 
axis of the instrument ; angle of site scale reading 300 when the 
line of sight is horizontal ; lost motion on worm gears eliminated. 
In principle, the adjustments of the B. C. Telescope and of 
the Aiming Circle are exactly the same. The leveling and 
focusing have already been described. Detailed instruc- 
tions of the operations in eliminating lost motion in the worm 
gears will be found in the Handbook for F. A. Fire Control 
Equipment, 1916. 

To make the site scale read 300 when the line of sight is 
horizontal. — Set up the telescope or aiming circle. Level the 
instrument so that the bubble on the azimuth worm case 
will remain centered while the instrument is turned 1600 mils. 
Lay on some point of a stake or other vertical linear object 
which is at a convenient distance but not closer than 100 yards 
to the instrument. The point selected should be at such a 
height that the telescope can later be set up close to it, with 
the objective at the same height as the selected point. Read 
the angle of site. This reading will be equal to (300 + S + 
E), in which S is the angle of slope of the line of sight, and E 
is the error in the site adjustment. Before leaving this station, 
set up a second stake near the telescope and mark on it a point 
which is at the height of the objective. 

Now move the telescope to the first stake ; set up and level 
the instrument with the objective at the height of the point 
marked on this stake. Lay on the marked point of the second 



278 FIELD ARTILLERY MATERIEL. 

stake and read the site. This angle will be equal to (300 — 
S X E). Substracting one reading from the other we have: 
— (300 X S X E) — (300 — S X E) = 2S; or one-half the 
difference of the two readings is equal to the angle of slope of 
the line of sight. Therefore with the cross wires directed upon 
the marked point of the second stake, center the bubble of the 
site level. Now loosen the angle of site locking screw and turn 
the micrometer to read (300 — S), being careful to keep the 
bubble centered. Screw up the locking screw. The instru- 
ment is now in adjustment. 

After one telescope has been adjusted, other telescopes, 
aiming circles and quadrants may be adjusted by merely 
measuring the site. 

After one telescope has been adjusted, other telescopes, 
aiming circles and quadrants may be adjusted by merely 
measuring the site of some distant point. The other telescopes 
and guns, being in position near the adjusted telescope, are 
then made to read the proper site when laid upon the distant 
point. 

FIELD ARTILLERY RANGE FINDER, 1 METER BASE 
(Bausch & Lomb.) 

The instrument and accessories consist of the range finder 
proper the tripod mount, the tripod, the adjusting bar, the 
carrying-case and the storage box. 

The optical parts of the range finder are embodied in a 
seamless, steel tube (A) covered with canvas and asbestos, to 
minimize the effects of the change of temperature. The eye- 
piece (B) is located in the center of the instrument and is 
equipped with a focusing device graduated in diopters. A soft 
rubber eye cap is furnished to protect the observer's eye from 
shocks and stray light. A ray filter having two sets of glass 
is operated by a small lever (C) situated to the lower left of the 
eyepiece housing. 



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280 FIELD ARTILLERY MATERIEL. 

The objective openings on the end boxes are opened and 
closed by means of rotating shutters (D). Buffers (E) are 
provided on the ends as a protection against shocks. 

The range finder is of the type known as the fixed base, 
invert, single coincidence. The magnifying power is 15; 
actual field of view 50 mils ; shortest distance measurable 400 
yards. The instrument weighs about 20 pounds. Under 
favorable conditions and with expert operators the average 
errors are: 

1000 yds 5 yds. 

2000 yds 15 yds. 

3000 yds 30 yds. 

4000 yds 55 yds. 

5000 yds 90 yds. 

6000 yds 130 yds. 

7000 yds 175 yds. 

8000 yds 225 yds. 

In practical use under ordinary conditions and with aver- 
age operators, the errors are three times as great. 

The tripod mount consists of a spring catch (a) ; clamp- 
ing lever (N); elevation worm case (b); elevation worm knob 
(c); worm wheel support (d); angle of site micrometer (e) ; 
angle of site housing (f ) ; angle of site vial holder (g) ; clamp 
screw handle (h); azimuth worm knob (i); azimuth microm- 
eter (j); azimuth worm lever (k); azimuth scale (m); adjust- 
ing worm knob (n) ; and the verticle spindle clamping lever 
(p). The tripod, consisting of spindle bushing locking screws 
(t) ; tripod legs upper (r) ; tripod legs lower (q) ; clamping wing 
nuts (w); and locking clamp arms (x), is similar to that pro- 
vided for the B. C. telescope and the aiming circle. 

Care and Instructions. 
T set up the Range Finder. — Set up the tripod as hereto- 
fore prescribed, take the range finder from its case, holding 




RANGE FINDER. 




RANGE FINDER. 



FIRE CONTROL EQUIPMENT. 281 

it with the eye piece toward the body, hook down. Place the 
instrument on the support and engage the spring catch (a); 
The instrument is then firmly seated on the tripod. Remove 
the protective hood from the eye piece and the rotating shut- 
ters (D) from the objective apertures. Loosen the locking 
lever so that the range finder may be made horizontal, then 
turn toward the target and clamp the lever. To dismount the 
range finder the operations are executed in an inverse manner. 

To Measure a Distance. — Focus the eye piece. In very 
bright light or in thick haze use the amber ray filter in the eye 
piece. By means of the clamps and worm knobs of the azi- 
muth mechanism and the worm knob of the elevation mechan- 
ism, lay the range finder on the target roughly by looking 
through the open sight on top of the instrument. Final 
adjustment in deflection is made by the adjusting worm knob 
(n) and in elevation by the elevation worm knob (c). 

Now, look into the instrument. The field of view is 
divided into two parts by a horizontal line. In the lower part 
the image is erect, in the upper part inverted. By turning the 
elevation worm knob (c), the images are lined up so that the 
same points will touch the dividing line. Now, by turning 
the measuring roller (M) on the right hand top side of the 
range finder, the upper image is shifted laterally until the same 
vertically disposed points of the target are exactly opposite 
each other. The range is then read on the range scale (H), 
which is protected by a sliding shutter (Q). 

In case the target is without prominent vertical features, 
such as a crest line, the distance is measured by first turning 
the instrument to a vertical position (Plate XV). This is 
accomplished by the clamp screw handle (h) on the tripod 
mount. Final adjustment in deflection is then made by the 
elevation worm knob (c), and in elevation by the clamping 
lever (N). 



282 FIELD ARTILLERY MATERIEL. 

Adjustments. 

Adjustment for Height. — The erect and invert images 
sometimes do not touch the dividing line with similar point 
so that one image reaches this line before the other. In this 
case, lay the range finder on an object having a sharply de- 
fined horizontal line or very prominent point, and bring the 
images of this point exactly opposite each other by means of 
the measuring roller (M). The two images are then brought 
to the dividing line, the lower image by means of the elevation 
worm knob (c), and the upper image by means of the halving 
adjusting roller (J). 

Adjustment for Range. — Three methods are available for 
adjusting the range finder for range; the artificial infinity 
method, using the adjusting bar; the actual infinity method 
using the sun, moon, star, or a very prominent distant point; 
the known range method, using a point the range to which 
is known. Of the three, the first is the best and should habit- 
ually be used. 

By the Adjusting Bar. — Set up the range finder; take the 
adusting bar and place it 100 yards from the instrument, 
sighting through the peep sight (y) of the adjusting bar 
and moving it until the range finder appears in the center 
of the field of view. Set the range scale at infinity by turn- 
ing the measuring roller (M), then make an observation 
on the adjusting bar. The right hand line of the upper image 
of the adjusting bar and the left hand line of the lower image 
should now be coincident, in which case the instrument is in 
adjustment (Fig. 10). If not, bring these lines in coincidence 
by turning the key which fits the square shaft (K), which oper- 
ates the range correction dial (L). This operation should be 
repeated at least three times, the reading of the range correc- 
tion dial being noted each time. Now, set the range correc- 
tion dial at the mean of the three readings. Remove the key. 



(1) 




(2) 




(3) 




THREE STEPS IN MEASURING A DISTANCE. 



FIRE CONTROL EQUIPMENT. 283 

The instrument is now in adjustment. Before using, always 
note the reading of the range correction dial. 

By the Actual Infinity Method. — This method is in all 
respects the same as the one with the adjusting bar, except 
for the images. After the instrument is set for infinity, actual 
coincidence is made as in paragraph 99. 

By the Known Range Method. — Operate the measuring 
roller (M) until the range dial reads the actual distance to the 
object. After the range finder has been set for this known 
range, actual coincidence is obtained by using the key which 
operates the range correction dial. 

FIELD GLASSES. 

The instruments for focusing the eyepieces and for ad- 
justing the interpupillary distance are the same as for the tele- 
scope. 

The two barrels should revolve easily about the central 
pivot and clamp in any position of the interpupillary scale. 

After being once adjusted, the field glasses should fit into 
the case without being changed. 

Carrying strap, button strap and rain shield should al- 
ways be part of the equipment. Amber shades and camels 
hair brush should be carried in the case for use. 

The vertical scale in the Type EE Field Glass represents 
the Infantry range scale and does not apply to Field Artillery. 

Compass should always be securely clamped except when 
in use. 

THE BRACKET FUZE SETTER, MODEL 1905 M. 

The bracket fuze setter is attached to the rear end of the 
fuze setter bracket on the caisson. It consists of the following 
principal parts: Base, housing, corrector-worm case, guide, 
range and corrector worms, rings, and scales. 



284 FIELD ARTILLERY MATERIEL. 

The corrector scale reads from to 60, numbered every 
10 points, 30 being the normal or mean arbitrary point. The 
range ring is graduated to 6400 yards, numbered every 500 
yards, least reading 50 yards. These rings are graduated for . 
the F. A. fuze on one side and for the Ehrhardt fuze on the 
other. Care should be taken that the proper side is up when 
firing the two different kinds of shrapnel. 

THE HAND FUZE SETTER, MODEL 1912. 

The hand fuze setter is provided for the same purpose as 
the bracket fuze setter, and is intended to supplement the 
latter. One hand fuze setter is issued in a leather case and 
is carried in the trail box of each gun. It is intended for the 
use in case the bracket fuze setter should become disabled, 
or in case the gun should for any reason be separated from its 
caissons. The principal parts are the case, the range index 
mechanism, range mechanism, corrector mechanism, and 
guide plate. 



SIGNAL EQUIPMENT. 285 



CHAPTER XV 
SIGNAL EQUIPMENT. 

CLASSIFICATION. 

The most important and widely used means of commun- 
ication used by artillery with their advantages and disadvan- 
tages follow: 

(a) Telephone. The telephone is the quickest and most 
satisfactory means of communication, and is the most gen- 
erally used of all means. Near the front, in areas subjected 
to fire it is often difficult to maintain lines and unless a line 
be a very carefully insulated and transposed metallic circuit, 
conversations held over it are picked up by the enemy listen- 
ing service. To guard against such information being of 
value to him, telephone codes have been devised, for use in 
important messages. 

(b) Radio. Radio provides a reasonably certain means 
of communication, but such messages are always intercepted 
by the enemy. Its use requires enciphered messages. 

(c) Projectors. Projectors afford a very reliable means 
of communition, but their use depends, to a great extent, on 
atmospheric conditions, and frequently they may not be used 
from rear to front and are slow in operation. 

(d) Flags. Semaphore and wig-wag prove fairly satis- 
factory only on exceptionally favorable conditions and in 
open warfare. 

(e) Runners. Used as a last resort. Slow and waste- 
ful but usually reliable. 



286 FIELD ARTILLERY MATERIEL. 

In each battalion (F. A.) there are a radio officer, tele- 
phone officer, and enlisted personnel for the maintenance of 
the communication system. 

The Camp Telephone. 

This telephone, which supersedes the field telephone, 
was developed by the Signal Corps for use in connection with 
camp telephone systems and small arms target range systems, 
and may be installed in tents and structures, or considered a 
portable instrument for use in the field for testing lines or other 
purposes. It is of local battery type. The battery employed 
is one unit of Tungston Type A which is made up of two 
small cells so placed in a rigid paper that they are connected 
in series. The combination gives a total voltage of 3 — lj 
being normal voltage of each cell. The instrument is made as 
compact as practicable and is contained in an oak case 4}^ 
x 7 x 10" high. The top consists of a metal hinged cover 
with circuit diagram on inside, held rigid when closed by a 
spring snap which can be readily released by depressing a 
button. The bottom of the case is covered by a flanged piece 
of metal, the flange projecting approximately one-half inch 
up sides of case. Through one side of the case are six three- 
eighths inch holes which are covered on the outside by a 
close mesh metal screen held in place by a metal frame. These 
apertures are for the purpose of allowing the ringer to be dis- 
tinctly heard. The case is equipped with a substantial, ad- 
justable carrying strap, each end of which is fastened to the 
case by means of hinged metal rings. A small 3-bar magneto 
generator, small ringer, induction coil, aluminum chamber for 
the single unit of tungston Type A dry battery, hard rubber 
block upon which are mounted line binding posts, plug con- 
nections for the handset used with the instrument, hook 
switch and hook operating it and auxilliary battery binding 
posts, are all mounted on a common base which may be readily 




THE CAMP TELEPHONE. 



SIGNAL EQUIPMENT. 



287 



removed from case after removing magneto generator crank, 
metal housing for it and three screws which extend through the 
case. The instrument may be operated with cover closed 
which is highly advantageous in inclement weather. To 
accomplish this there is a suitable opening for leading out the 
3-conductor cord to receiver and transmitter the two latter 
being mounted in the form of a unit, termed a handset. This 
handset consists of a transmitter and a receiver mounted on 
a metal piece and is so designed that when the transmitter is 
normally placed to the mouth, the receiver is automatically 
adjusted to the ear. The hook of hook switch is so designed 
that it protrudes through the case. When it is desired to 
transport the instrument or to remove the base upon which 
is mounted all parts of the instrument, it is merely necessary 
to depress the hook and push it toward the base. By this 
arrangement the hook is not only held in the down position 
thereby opening the battery circuit, but it is also protected. 
The aluminum chamber for housing the single unit of tungston 
type A battery is equipped with a spring catch so located 
that when upper hinged piece is depressed to proper position, 
the battery compresses a helical spring, thereby insuring con- 
tinual contact. The base is equipped with two screw binding 
posts which may be used to connect leads to an outside battery 
in the event of there being no tungston type A batteries avail- 
able. An aluminum frame which is supported on the base 




job I 



t*\<i£ft*ts> 



c\ 




288 FIELD ARTILLERY MATERIEL. 

previously mentioned forms a compartment for the handset 
when instrument is being transported. When the instru- 
ment is installed for a temporary period, unless in actual opera- 
tion, the proper place for the handset is hanging on hook of 
hook switch, there being a ring on the handset for this pur- 
pose. A small screwdriver which will fit practically all the 
screws used in the construction of the instrument is sup- 
ported by the metal frame and is furnished with each instru- 
ment. The instrument complete weighs about 11 pounds. 

The Monocord Switchboard. 

The liaison of telephone inter-communication between 
army units is frequently such that a temporary, quickly in- 
stalled and flexible type of small central exchange located in 
the field, is essential. Such an exchange is usually placed in 
a well protected dugout at the infantry battalion headquarters, 
artillery battalion headquarters, central artillery observation 
post, etc., where it will be the central terminal point of from 
four to twelve or more lines connecting with the headquarters 
of the higher command, with the several units working with 
the battalion, and with the joining similar battalions. The 
switchboard which has been designed to meet these require- 
ments is called the "monocord switchboard" and is made up of 
either four, eight or twelve of the type EE-2 switchboard 
units. 

The monocord switchboard is made up of unit panels, on 
each of which is mounted all the apparatus needed for the 
central exchange end of one telephone line. These panels 
are made of insulating material and are mounted in special 
wooden frames in groups of four, eight and twelve units, ac- 
cording to the size of the installation necessary. The two sizes 
most commonly used in overseas work are the four unit and 
twelve unit boards. Each unit is removable from the frame, 
thereby lending flexibility to the board and facilitating repair 



SIGNAL EQUIPMENT. 289 

and replacement. Generally, this type of board is used only 
for a small number of lines as the operating facilities do not 
permit speedy connections, and it is always, better practice 
to use only three lines on a four unit board and 11 lines on a 
twelve unit board in order to have a spare unit immediately 
available. 

The monocord switchboard may be used with either a 
magneto telephone, camp telephone, field telephone Model 
1917, buzzerphone or service buzzer. The operator's tele- 
phone set is not furnished as a part of the switchboard and a 
separate telephone set of one type previously mentioned must 
be supplied for this purpose. 

Switchboard Frame. — The switchboard frame is made of 
hard wood, varnished in order to make it moisture proof. Its 
function is to hold the various units together and to protect 
them from dust and mechanical injury. In the back of the 
frame there are three horizontal brass bars extending the 
width of the board. In addition to providing a mechanical 
support for the various units, the top bar serves as a common 
ground connection and the middle and bottom bars as common 
night bell and battery connections for all units. Three Fah- 
nestock clips on American made boards and binding posts on 
French made boards are installed at the top of the frame and 
four at the bottom,. On the French made boards the upper 
three binding posts are marked SI, S2 and T, and are used for 
connecting by independant wires, respectively, the night bell 
and ground. The two posts at the bottom of the frame 
marked ZS and CS are used for connecting the two poles of 
the night bell battery. To the other two marked PI and P2 
are connected the operators telephone and the operators plug. 
The terminals at the top of the American made boards are 
marked A, Al and G, corresponding with the French SI, S2 
and T, and those at the bottom are marked B, Bl, LI and 
L2, corresponding to ZS, CS, PI and P2, respectively. 



290 FIELD ARTILLERY MATERIEL. 

If two or more multi-unit boards are connected in parallel 
for operation at one exchange, the interconnections between 
boards in order to use one ground, one night bell and one 
battery for the whole exchange are made. The correspond- 
ing binding posts at the top and bottom of the frames are 
simply connected to each other, as SI and S2 of No. 1 board 
to SI and S2, respectively, of No. 2 board. 

Unit Panel. — Each unit comprises all the necessary ap- 
paratus for the exchange terminals of one line (two wires). 
The various parts are listed below according to their position 
on the panel from top to bottom: 

Two connecting blocks for the line wires. 

Lightning arrester between these blocks. 

Two fuses. 

Line number plate. 

Line drop signal and night bell contact. 

Jack. 

Cord and line plug. 

Each unit is held in the frame by means of two machine 
screws, one at the top and one at the bottom of the unit, which 
engages the brass bars in back of the board and hold the 
unit firmly in place. Rigidity of construction is essential, as 
constant use and transferring from one place to another tend 
to loosen the units from the frame and disturb the sensitive- 
ness of the adjustment of the line drop. 

Lightning Arrester. — The lightning arrester is a simple 
toothed washer held against the panel by the supporting 
screw. This screw is grounded through the upper brass bar. 
If lightning comes in on the line wires, the main portion of 
it jumps the small air gap from the binding post to the 
grounded washer and thence passes to the ground, so that 
only a small portion of the high frequency current flows 
through the switchboard apparatus. If the latter portion 



SIGNAL EQUIPMENT. 291 

is at all heavy, the fuses burn out, opening the circuit through 
the switchboard with a much wider gap, and hence higher 
resistance than that in the circuit to ground across the ar- 
rester. 

Line Fuses. — Two glass enclosed removable fuses, which 
fit into spring connections, are provided to protect each side 
of the line from excessive currents. In order that burned out 
fuses may be readily seen, the panel is painted white behind 
them. The glass is usually smoked up more or less when a 
fuse burns out and this against the white background is easily 
noticed. 

Line Number Plate. — The line number plate is a small 
white celluloid strip on which the line number is written. 
This number may easily be erased if it is necessary to change 
it. 

Line Drop Signal. — The line drop signal consists of a shut- 
ter held normally in a vertical position by a brass trip latch. 
This trip latch is attached to the armature of a small electro- 
magnet which is normally connected across the line through 
the anvil and the jack tip contact spring of the switchboard 
jack. When the coils of the magnet are energized by a cur- 
rent sent over the wire from a calling station, the armature 
and trip latch are lifted, thereby releasing the shutter, which 
falls by gravity to a horizontal position and attracts the at- 
tention of the operator. The electromagnet is adjusted to 
operate on a very small current. For locking the shutter in 
the vertical position and protecting it from mechanical injury 
during transport, a flat spring lever is provided which may 
be turned up from a pivot at one to press against the shutter. 

Night Bell Spring Contact. — The night bell contact is 
located in the back of the panel. The battery and bell cir- 
cuit through this contact is closed when the line signal drop 
shutter is released by the electromagnet, this forcing the 



292 FIELD ARTITLERY MATERIEL. 

spring back against the contact point. The night bell spring 
contact consists of a narrow flat brass spring, screwed at one 
end to the drop mounting plate. The contact point is mounted 
on the back of the panel, the rear end of this rod making con- 
tact with the night bell bus bar, against which the rod presses 
when the panel is screwed in place on the bars along the back 
of the switchboard. 

Switchboard Jack and Line Plug. — Each unit is pro- 
vided with a jack and plug. The jack consists of a cylindrical 
opening in the panel of the unit, behind which are arranged 
the tip contact spring, the sleeve contact spring and the anvil. 
The tip spring is connected through one of the fuses to one of 
the line wires. The anvil is connected to the other line wire 
through the electromagnet coils and the other fuse. The 
magnet circuit is normally closed across the line when there 
is no plug in the jack, as the tip spring and the anvil are then 
contact. A current coming in over the line, then, would ener- 
gize the coil. The sleeve spring of the jack is connected 
directly to the same line wire as the anvil, the line plug is 
bridged across the tip and sleeve contact spring. It is a stand- 
ard two-contact type, the tip and the sleeve making direct 
connection to the line. 

Operator's Equipment. — Any equipment which is not in- 
dividual to a line, but which is used in common to all lines in 
the process of interconnection, is called the operator's equip- 
ment. This consists of an ordinary telephone set, employ- 
ing either magneto or buzzer and including a transmitter, 
receiver, induction coil, generator, battery and connection, 
together with the wiring and the associate parts necessary to 
co-ordinate them with the rest of the apparatus. An operator's 
equipment also inculdes a night bell and battery. 

Carrying Case. — Carrying cases made of fiber and pro- 
vided with hand straps are furnished with monocord switch- 



SIGNAL EQUIPMENT. 293 

boards to provide a convenient means of carrying them and 
to protect them from damage during transportation. These 
cases are made so that they will hold not only the frame with 
the assemble unit, but also the switchboard cords. To move 
the board it is necessary to disconnect the night bell battery, 
the night bell, the ground connection, the operator's set and 
the several line wires. 

Care and Adjustments. — Care must be exercised when a 
board is installed to make sure that the frame is in a vertical 
and level position. When assembled at the factory, all ad- 
justments are made with the board in a vertical position 
and all operations conductive to satisfactory service depends 
on this prerequisite being observed. The line signals of the 
monocord switch boards are of the gravity type and re- 
quire careful adjustment. Any adjustment further than that 
done at the factory should be made by an expert who is thor- 
oughly familiar with this work. During transportation and 
installation of this board, the line drop shutters should be held 
closely by the flat springs previously described. The burning 
out of a fuse when excessive current comes in on a line that is 
detached by an open circuit on that line. A bad fuse generally 
shows plainly against the white background on the panel. 
However, if it is not possible to see whether or not the fuse is 
burned out, the line may be short circuited momentarily by 
means of a piece of bare copper wire placed across the two line 
terminals. The operators is then inserted in the jack of the 
unit under test, and the magneto crank turned. If the fuse 
is burned out, the crank will turn over easy; if not, it will 
turn hard, indicating that the open circuit is elsewhere on the 
line. A burned out fuse should be replaced immediately in 
order to keep all lines working. Several spare fuses should 
be kept on hand at all times but in case no fuse is available, a 
strand of small copper wire may be connected across the upper 
and lower fuse clips. To remove a fuse, take the bottom metal 



294 FIELD ARTILLERY MATERIEL. 

cap of the fuse between the thumb and finger and push up- 
ward against the spring holder on the line terminal block, at 
the same time pulling outward. To install a fuse, hold it in 
the same manner and put the other end of the fuse in the upper 
spring contact, forcing it upward until the bottom ends slip 
into place. Care should be taken to keep the small air gap 
between the toothed washer and the line terminal clean. If 
this precaution is not taken, and the air gap is allowed to clog 
up with dust and dirt, it will introduce a leak to ground or 
between wires with resulting poor transmission. All mount- 
ing screws and all wire connections should be kept tight. 
Whenever the unit is damaged, it should be replaced by 
another one, the damaged unit being sent back to headquar- 
ters for repair. In this connection it should be noted that the 
American unit panels and parts have been made interchange- 
able with the French to facilitate repair. To remove a unit 
from the frame, it is only necessary to disconnect the line term- 
inals and remove the top and bottom screws which engage the 
brass bars behind the board. In handling the switchboard 
cords, they should be grasped by the plug, not by the cord. 
The connection of the wires to the tip and sleeve of a plug 
will break, is subject to undue strain or abuse, and by taking 
hold of the plug while inserting it and pulling it out, the likeli- 
hood of breaking the internal connections and wearing out the 
wires will be reduced to a minimum. 

Disadvantages of the Monocord Switchboard. 

1. It does not afford as quick connections as the by-cords 
switchboard type. 

2. It is not self-contained. A self-contained switch- 
board includes operators, receiver and transmitter and ring- 
ing and night alarm circuits. 



SIGNAL EQUIPMENT. 295 

3. The operator's telephone is usually equipped with a 
hand set, (receiver and transmitter) which leaves him with 
only one free hand for making connections. 

4. One switchboard is equipped with but one master, 
or operators cord, this affords only one means of answering 
and calling. 

Advantages of the Monocord Switchboard. 

1. Small, compact, light weight. 

2. Simple wiring. 

3. Quickly installed. 

4. Particularly suited for small central exchanges. 

5. Units can be removed quickly, in case of trouble in 
interior circuits. Any unit can be removed without dis- 
turbing other units. 

Common Faults and Remedies of the Magneto Telephone. 

The most common trouble in telephone instruments are 
due generally to one of three causes. (1) Loose or dirty 
connections at the binding posts of the instrument, at the 
binding posts of the batteries, or in joints of the line wires, 
(2) exhausted, poor, or weak batteries, (3) crossed, open, or 
defective wires. These troubles, of course, do not include 
those arising from inferior or defective instruments. If the 
connections are dirty, corroded or greasy, scrape the wires 
and clean out the binding posts, then screw the wires firmly 
in place. If the telephone does not then work properly, 
examine the batteries and see whether they are run down or 
whether the zincs are eaten away. With wet batteries, it 
may be possible that the water has evaporated; in dry bat- 
teries, the zincs may be eaten through or the batteries 



296 



FIELD ARTILLERY MATERIEL. 



may be otherwise defective. The simplest way to test a 
battery is to try a new battery, and see whether it will make 
the telephone work properly; if it does, the trouble is with the 
old battery. If the trouble is present after changing the 
battery, examine the line connections and the line outside; 
if any loose connections are found, correct them at once. 
When inspecting the line outside see that it does not touch 
anything except the insulators, and that it is neither crossed 
nor broken. On grounded lines — grounded lines are obsolete 
now in modern warfare on the account of the many means of 
detecting and picking up messages now employed; in fact the 
metallic circuit telephone lines are now used within a mile of 
the front lines except for messages which would be of no value 
to the enemy — examine the ground connections the first thing 
and see whether it is in good condition, and if a plate is used 
see that it is in moist ground. The frequent trouble with 
transmitters is the frying noise; that is usually caused by in- 
duction or static electricity, and may also be caused by loose 
connections. 



1. Open Line. 



( Effect: Cannot receive a call or get central. 

J Test: Follow line with portable magneto 
test set and ring; if central gets ring, open 
is toward station or visa versa. 



2. Open Battery. 



Open primary wind 
ing. 



4. Open Transmitter. 



Effect: Can hear and receive central call 
but cannot talk. 

Test: Strap out primary winding or trans- 
mitter with test receiver, and leaving the 
receiver off the hook at station, listen 
in either for click while moving switch- 
hook up and down. If no noise be 
heard, battery circuit must be open, and 
circuit should be followed with test re- 
ceiver, which will click loud where bat- 
tery is found to be O. K. 



SIGNAL EQUIPMENT. 



297 



5. Short Circuited 

Line. 

6. Wet or short Cir- 

cuited Instrum't. 



Effect: No signal will show at magneto 
switchboard, and use of station instru- 
ment will be imparied and magneto will 
turn hard. 

Test: Open line and ring; if magneto still 
turns hard open connections one at a 
time, where available throughout entire 
winding until magneto turns freely. 



Line crossed with 
another line. 



Effect: Other talking heard on the line 
when the receiver is off the hook. 

Test: Ring magneto and with central's help 
try to locate other party; then trace line. 



8. Open secondary 

winding. 

9. Open receiver. 

10. Receiver diaphragm 
missing or badly 
dented. 



Effect: Can ring and hear central ring but 
cannot hear in receiver although can be 
heard. 

Test: Strap test receiver across open part. 



11. Weak battery Cells. 



Effect: Can hear well but cannot be heard 

clearly. 
Test: Use ampere meter and see if each cell 

be weak. 



12. Open Bell. 



Effect: Can talk and hear in receiver but 

bell does not ring. 
Test : Strap bell coils out with test receiver 

and listen in. 



13. Open magneto Ar- 
mature Winding. 



Effect: Bell rings from central but does 
not ring when magneto handle is turned 
nor can central be called. 

Test: Ring with another magneto or test 

{ set. 



298 FIELD ARTILLERY MATERIEL. 

| Effect: Can ring operator but cannot hear 

nor be heard clearly. 

14. Slight Short Circuit | Test* Open line, one line at a time, and 

(escape) to <! follow circuit with test set. Escapes are 

Ground. due to wires touching damp walls, metal 

roof, or other grounded wire where in- 

I sulation has been rubbed off. 



Signaling by Means of Lamps. 

Visual signaling by means of the lamp has been found to 
be very important and efficient. Experience has shown that 
during the first hours of a battle, particularity in an advance, 
before it has been possible to establish the telephone systems, 
the lamp has furnished the most dependable means of com- 
munication both by day and night. Even in stationary or 
trench warfare in sectors with well organized systems of com- 
munication, the lamp is most serviceable in transmitting 
short messages such as calling for a barrage, reinforcements, 
etc., for which arbitrary signals are used. In fact, this method 
is more precise than the use of rockets and more rapid than the 
telephone in transmitting information covered by these arbi- 
trary signals. For these reasons, all important telephone 
lines near the front are paralleled by the lamp system. 

Description of the Lamps. — The signaling lamps are made 
in three sizes called the 14, 24 and 35 centimeter lamps. These 
dimensions indicate the diameter of the reflector. The 24 
cm lamp consists of a portable searchlight, similar in prin- 
cipal to an automobile headlight, but equipped with a sighting 
or aiming tube on top, a hinged lid to cover the glass reflector, 
and a two-wire cable used to connect the batteries for operat- 
ing the bulb. The battery comprises eight dry cells in series, 
carried in two leather pouches, each holding four cells. These 
pouches are attached to a leather belt supported by shoulder 
straps. The belt has also an additional pouch in which three 



SIGNAL EQUIPMENT. 299 

extra lamp bulbs are carried. A brass push button which 
projects through this pouch is used as a key in completing 
the battery and lamp circuit to make signals of short and long 
flashes. Connection between the lamp and battery is com- 
pleted by the two wire cable and the plug and socket con- 
nector. The complete apparatus, comprising the lamp and 
the belt and three spare light bulbs and eight dry batteries, is 
furnished in a wooden carrying case. The 14 cm lamp is 
similar to the 24 cm, but smaller, using a battery of four dry 
cells and being slightly different in the manner in which it is 
carried. The 14 cm lamps come three in a wooden case with 
extra batteries and lamp bulbs. The 35 cm lamp is a larger 
model of the 24 cm lamp, is not as readily portable and em- 
ploys a storage battery. It is used only for permanent in- 
stallations. 

Method of Operation. The lamp and battery circuit is 
completed by means of the plug and socket connector. The 
lid covering the reflector is then opened and the operator sights 
through the tube to locate the station with which he is to 
communicate, and signals by means of the push button key. 
It is essential that the lamp be held rigidly and the sighting 
tube be continuously aimed exactly at the receiving station 
during signaling. A slight movement of the lamp makes the 
signals appear blurred or entirely invisible to the receiving 
station. A lamp station should always be located in the shade 
or protected from direct sun rays, which would otherwise pro- 
duce a continuous glare from the reflector and make the elec- 
tric light signals invisible. A lamp may be held in the hand 
while signaling or fastened to anything that will aid stability. 
In permanent and semi-permanent stations an arrangement 
for holding the lamp in a fixed position, directed at the re- 
ceiving station, should be installed. In addition, a wooden 
tube tapering down in size toward the outer end and being 
6 ft. to 9 ft. long and approximately the size of the lamp at the 



300 FIELD ARTILLERY MATERIEL. 

inner end, should be constructed and also permanently aligned 
on the receiving station. This reduces the diffusion of the 
rays of the lamp, and also minimizes the possibility of the 
signals being read where not intended. 

Adjustments of Lamps. — The reflecting apparatus of a 
lamp is carefully adjusted before it is issued. However, it is 
possible that a slightly different adjustment will give better 
results when a new bulb is inserted. To focus the lamp the 
light is flashed on some dark background, such as wall a few 
yards away, and the screws supporting the parabolic mirror 
carefully turned until the light becomes concentrated in the 
smallest possible circle. The adjustment screws are then 
tightened, but they should never be set tight. If the receiving 
operator is having trouble in receiving signals, he will inform 
the sending station by sending a series of dots. The sending 
operator will then examine his apparatus to see if the lamp is 
properly directed at the receiving station, if the reflector is 
out of focus, or if the battery has become weak. The receiv- 
ing operator indicates the manner in which he is receiving the 
signals by the method in which he sends the dots. If the 
signals become worse, the dots are made more rapidly. As 
the adjustment becomes better, the dots are made more 
slowly. When a good readable adjustment has been obtained, 
he will signal BR, meaning "go ahead." 

PRECAUTIONS IN LAMP SIGNALING. 

Don't leave the lamp cover open when not in use. 

Don't forget to open it when you start to transmit. 

Don't touch the mirror. If necessary, it should be cleaned 
by wiping with gauze or cotton or wiped with clean water. 

Don't pull the wire cable fastened to the bottom of the 
lamp when removing from the box. 



SIGNAL EQUIPMENT. 301 

Don't return broken or burned-out globes to the pouch, 
but throw them away unless ordered to turn them in. Don't 
use the lamp for illuminating purposes. 

Don't neglect to keep a constant watch on the stations 
with which you are supposed to communicate. 

SIGNALING RANGE OF LAMPS. 

Day. Night. 

14 cm 1 to 3 kilometers 2 to 6 kilometers. 

24 cm 1 to 6 kilometers. . . 3 to 10 kilometers. 

35 cm 5 to 10 kilometers 8 to 15 kilometers. 

Signals may be transmitted by using either white or red 
bulbs, but the range when using red bulbs is reduced ap- 
proximately 50%. 

GENERAL SERVICE CODE AND CONVENTIONAL SIGNALS FOR 
USE WITH PROJECTORS, BUZZERS AND WIGWAG. 

A.- G--. M-- S... Y-.-- 5 

B -... H .... N-. T- Z--.. 6-.... 

C-.-. I.. O U ..- 1. 7--... 

D-.. J. P.--. V...- 2.. 8 .. 

E. K-.- Q--.- W .--. 3...-- 9 . 

F..-. L.-.. R .-. X-..- 4....- 10 

Manner of Sending Messages. 

Messages are sent by using the General Service Code and 
should always be as short as possible. Every time a letter 
can be omitted, the chance of error is reduced. A dot is made 
by a short flash of about J second duration. A dash is a 
longer flash of about two seconds duration. The interval 
between dot and dash is about | second duration. The in- 
terval between letters is about 2 seconds duration. The 
interval words is about 4 seconds duration. In order that 
lamp signals may be easily read, it is necessary that the signals 
be not too rapid, 15 to 20 characters per minute should be 



302 FIELD ARTILLERY MATERIEL. 

taken as the upper limit. Successive letters must be well 
spaced. An interval of 2 seconds between letters will enable 
the receiving operator to call off each letter to his assistant as 
he receives it. In general, two men for each shift are neces- 
sary to operate a lamp station. At the sending station one 
man dictates the message letter by letter, and watches the 
receiving station for breaks. The other sends the message. 
At the receiving stations, one man receives the message and 
calls it off by letter to his helper who writes it down. To call 
a station, its call letter should be sent several times and at 
intervals the station calling should signal its own call letter. 
As soon as a station observes that it is being called, it will 
answer by signaling its call letter and the signal BR, "go 
ahead." The message is then transmitted and the receiving 
station acknowledges receipt of each word. By one dot, if it 
has been understood. By the interrogation mark, if it has 
not been understood and repetition is desired. (While the 
interrogation is official, two dots are invariably used for this 
signal.) At the end of a message the sending station signals 
AR, meaning, "end of message." The receiving station sends 
a dot if the message has been understood. 

Signaling by Means of Fireworks. 
The use of fireworks in modern battles for sending signals 
has been greatly developed and is now one of the most im- 
portant means relied upon to send a few fundamental signals 
from the front line of the infantry to the supporting artillery 
within the division and between the ground and the airplanes. 

The Fireworks Code. 

As the signals that are made by fireworks are always of 
the most important character, it is essential that the system 
for their use be so perfectly worked out that there will be no 
chance of confusion. The smaller the number of signals to 
be sent by fireworks, the less chance there is of confusion. 



SIGNAL EQUIPMENT. 303 

Classification of Fireworks. 

The fireworks now being used by the American Army are 
divided into the following classes: 

1. Very Pistol cartridges. 

2. VB cartridges (commonly called "Tromblons"). 

3. Rockets 

4. Flares. 

The complete directions for firing these various fireworks 
are generally attached to the container or box in which they 
are packed. They are fully discussed in Annex 14, Translation 
of the 1917 ''Instruction on Liaison for Troops of all Arms, 
A. E. F." 

1. Very Pistol Cartridges. 

The Very pistol cartrdiges are made in two sizes, a 25-mm 
size, which is issued to the companies of infantry, and a 35- 
mm size, which is used by the airplanes. These Very pistols 
fire both signal and illuminating cartridges. 

2. VB Cartridges. 

The VB cartridges are fired from a cylinder which is at- 
tached to the end of a rifle. This cylinder, on account of its 
resemblance to the old-fashioned blunderbuss (which the 
French call "Tromblon") has taken the name of tromblon and 
now even the VB cartridges, which are fired from this cylinder, 
are often spoken of as Tromblons. 

3. Rockets. 

The rockets comprise fireworks which are made in the 
form of cartridges attached to a wooden stick and fired from 
a tube or trough. They are used both for signaling and il- 
luminating. 

T. B.— 20 



304 FIELD ARTILLERY MATERIEL. 



4. Flares. 

Flares are used only in the front lines to mark the posi- 
tion of the advanced troops when called for by an airplane. 

THE USES OF VARIOUS CLASSES OF FIREWORKS. 

It will be seen that the above classification of fireworks 
is an arbitrary one, made according to the method of projec- 
ting them. The same signal can be made by several different 
means. The means employed depend upon the type of fire- 
works issued to the particular unit using them and also upon 
the distance through which the signal must be read. 

Flares are not projected at all and consequently have the 
most limited range of visibility in any but a perpendicular 
direction. 

The 25-mm Very pistol projects its signals about 200 ft. 
and can be seen from the immediate vicinity. 

The tromblon projects its signals to a height of 300 ft. 
and is next in range of visibility. 

The rockets which project a signal at the height of 1000 
ft. or over have the maximum range of visibility. 

The 35-mm Very pistol projects signals which are larger 
than those of the 25-mm pistol, but throws them a shorter dis- 
tance (about 150 ft.). As its use is confined to the airplane 
this is not a factor in its visibility. 

The following are important uses that may be made of 
fireworks : 

1. By the infantry platoon, company or battalion com- 
mander in signaling to the artillery for a barrage, or other- 
wise directing the fire of the artillery. 

2. For signaling between the front line troops and the 
contact airplane in an advance. 

3. Warning of enemy gas attack given by the fireworks 
signaler nearest to where the gas is discovered. 



SIGNAL EQUIPMENT. 305 

4. As a method of acknowledging various visual signals. 

5. Occasionally, during the preparation of an attack and 
upon orders from the General Staff, fireworks may be used in 
liaison between the artillery and the artillery airplanes. 

Signaling by Means of Panels. 

The increasing use of the airplane in modern warfare has 
necessitated the development of reliable communication be- 
tween it and the earth. This has gradually been worked out 
in the following methods: 

1. The direct dropping of messages by the airplane. 

2. The use of radio apparatus. 

3. The use of visual signaling by means of lamps, 
fireworks and panels. 

Panels are pieces of cloth or other materials of various 
designs which are spread out on the ground in a manner to be 
easily seen by the airplane. They are for three purposes. 

1. To signal to an airplane the identity and location of a 
unit's headquarters by the use of its distinctive panel, called 
its "identification panel." This is displayed either when the 
airplane requests it (by means of radio) or when the head- 
quarters desires to attract the attention of the airplane. 

2. To signal to the airplane other brief information by 
the use of rectangular panels known as "signaling panels" 
and arranged in various ways, either by themselves or in con- 
junction with the unit's identification panel. 

3. To signal to the airplane the position of the front line 
in a daylight advance by the use of special panels called 
"marking panels." These are displayed only when called 
for by the airplane. 

All panels are removed as soon as an acknowledgment is 
received from the airplane. 



306 FIELD ARTILLERY MATERIEL. 

As the use of panels is always in conjunction with air- 
planes, all panel signallers should understand some of the 
uses of the various airplanes. 

Miscellaneous Methods of Visual Signaling. 

Wig- Wag Flags. — Flags for use in wig- wagging are now 
issued to divisions under the name of "kits, flag, combination, 
standard." Each kit includes one wig-wag staff and two wig- 
wag flags, and also two semaphore staff and two semaphore 
flags. A division is supplied with 1,022 of these kits. The 
use of the wig-wag flags is already fairly well known in the 
American Army. Signals are transmitted by describing an 
arc of 90 degrees to the right and left to form dots and dashes, 
and spaces by a downward front motion. The general serv- 
ice can be transmitted by this means. Wig-wag flag signaling 
should be thoroughly understood and practiced by all signal 
men, as it forms an excellent method for becoming familiar 
with the code. Signals can be sent by this means merely by 
the use of the hand, and consequently the system forms an 
excellent way for troops to put in their time when traveling 
by train or on shipboard. Its use in the present war has been 
limited, but it will undoubtedly be used more and more, es- 
pecially when open warfare is resumed. 

Semaphore. — Signals by semaphore are transmitted by 
the arms, either alone or with the semaphore flags that are 
issued in the standard combination flag kits. It is a standard 
means of communication in the American Navy and well 
known in the army. It is not used by the armies of Europe, 
but it might serve a useful purpose to linemen and others for 
intercommunication. 

Radio Equipment. 

The Radio receiving sets, type SCR-53 and SCR-54-A 
form the standard units for the reception on the ground of 



SIGNAL EQUIPMENT. 



307 



signals from airplanes, and in general, of all damped wave 
signals or modulated wave signals. The use for these sets 
may perhaps be said to be that in connection with the work of 
the fire control airplanes in directing the fire of the artillery. 
But in addition, they are used for so many other classes of 
radio work, that they may indeed be considered among the 
most important radio sets. 

Type SCR-54 Set. 

The type SCR-54 set is very similar to the French type 
A-l receiving set. The SCR 54- A set is an improved American 
product, designed along the same general lines as the type SCR 
-54 but differing in some respects, both mechanical and elec- 



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phlet No. 2. With their use the receiving sets have a wave 



308 FIELD ARTILLERY MATERIEL. 

length range of approximately from 150 to 650 meters. If 
properly operated, they afford quite sharp tuning. This fea- 
ture and their compact, rugged and simple construction have 
made of very considerable value on the Western Front. 

As shown in the wiring diagram, Fig. 1, the typeSCR-54A 
receiving set comprises a primary (antenna) circuit and a 
secondary circuit, both of which may be tuned by means of 
the variable capacitance and variable inductance comprised 
in both circuits. The secondary circuit may also be made 
aperiodic by placing the switch M on the position marked 
"AP." This connects the condenser in or disconnects it 
from the circuit. A separate buzzer circuit is installed in the 
cover of the box to excite the set when adjusting the crystal 
detector. 

The adjustable capacitance in each circuit is a variable 
air condenser which is adjusted by means of an insulating 
handle, marked "Primary" or "Secondary," mounted directly 
on the rotating shaft of the condenser. The relative amount of 
capacitance in the circuit, corresponding to the various posi- 
tions of these handles, is indicated by a pointer fastened to the 
shaft, which moves over a dial graduated from to 90. The 
position corresponds to the minimum and the position 90 
to the maximum capacitance of the condenser. The two con- 
densers are identical in design, and have a maximum capaci- 
tance of 500 micro-mfd. 

The primary and secondary inductances are varied by 
means of two dial switches marked "P" and "S," respectively. 
The primary inductance comprises 60 turns of wire divided 
into six steps of 10 turns each, while the secondary inductance 
comprises 60 turns divided into four steps of 15 turns each. 
These two inductance coils are wound on separate wooden 
cylinders so arranged that their relative positions may be 
readily varied. The coupling of the two circuits, which is 
accomplished by the mutual induction effect of these two coils, 



SIGNAL EQUIPMENT. 309 

is varied by changing the relative mechanical positions of the 
coils. The secondary coil may be rotated by means of a 
handle marked "Coupling," and a pointer moving over a scale 
graduated from to 90 indicates its position. When in the 
position the axes of the two coils are at right angles to each 
other, and the degree of coupling is 0. When in the position 
"90" the axes are parallel, and the coupling is a maximum. 

The telephone and detector circuit shunts the secondary 
condenser. This circuit consists of a crystal detector connec- 
ted in series with the telephone receiver which are shunted by 
so-called stopping condensers. The latter is a .002 mfd. mica 
condenser. Two crystal detectors are furnished with a set; 
one of them is enclosed in a glass tube, which protects the 
crystal from dust or dirt. The other is open, having no such 
protecting casing. Either one may be used by screwing it 
to the two binding posts of the set marked "Detector." 

The buzzer is mounted in a compartment of set box 
cover, and consists of a small buzzer connected in series with a 
dry battery type BA-4, and a switch. The buzzer is energized 
when this switch is closed. A spare dry for the buzzer, a 
screwdriver, the enclosed detector, some spare wire and spare 
crystals are normally stored in compartments or metal clips 
in the cover. Two type P-ll telephone head sets are kept in 
a special compartment in the box. This set box when closed 
may be carried by a leather strap attached to it. 

Method of Operating. 

The first step in putting the set in operating condition is 
to select a suitable place and set up the antenna. The set 
box is then installed in a dry and protected place, and the 
arial and ground (or counterpoise) leads are connected to 
their respective terminals on the operating panel, and the 
telephone head set plugged into the jack with the installation 
thus completed the first step is to adjust the crustal detector. 



310 FIELD ARTILLERY MATERIEL. 

To do this, place the "Coupling" handle near the maximum 
position, and connect the short piece of wire from the terminal 
clip in the buzzer circuit to the "Antenna" or "Ground" 
terminal of the operating panel. Close the buzzer switch 
to energize the buzzer, and carefully explore the surface of the 
crystal with the spring contact point until a sensitive spot is 
found, as evidenced by a good audible sound in the telephone 
receiver. The short wire running from the buzzer to the panel 
is then removed and the buzzer stopped by opening the buzzer 
switch. Care should be taken not to disturb the crystal ad- 
justment by mechanical vibration or shock. This adjustment 
is very delicate, and if destroyed, it must be restored before 
any signals can be received. With the crystal adjusted, the 
set is then ready for tuning. The procedure varies somewhat 
according to whether the wave length of the station it is de- 
sired to receive is known or not. 

(a) Wave Lengths of Signals Unknown. — The switch 
M in the center of the panel is thrown to the position "AP" 
(aperiodic). This disconnects the secondary condenser, and 
makes the secondary circuit responsive to signals of any wave 
length. The coupling is made a maximum, and the secondary 
inductance dial switch S placed at the position "60." The 
primary inductance switch P is then placed successively at 
the positions marked 10, 20, 30, 40, 50 and 60, and, at each 
point, the handle of the primary condenser is slowly turned 
over its full range, until the loudest signals are obtained in the 
telephone. The station is then identified by its call letters, 
and if it is the station desired, tuning of the set is completed 
as explained below. It may happen however, that in this 
search for signals, several stations are heard, simultaneously 
or for different positions of the handles. The process of search- 
ing is kept up until the desired station, as identified by its call 
letters, is heard with the greatest intensity. 



SIGNAL EQUIPMENT. 311 

The coupling pointer is then moved toward the minimum 
position, so that the signals will be just loud enough to be 
easily read. The switch M is placed in the position T (tune), 
which connects the secondary condenser in the secondary cir- 
cuit. The secondary circuit is then tuned by operating the 
secondary inductance dial switch S and the secondary in the 
same way that was followed in tuning the primary. The sec- 
ondary circuit is in tune when the signals are heard loudest. 
The set is then ready for operation. 

If necessary, the strength of the signals may be increased 
by increasing the coupling, but this should not be done unless 
the signal become too faint to be read, since increasing the 
coupling increases the likelihood of interference by other send- 
ing stations. When the coupling is changed, some slight 
adjustments of the primary and secondary condensers will 
be found to improve the signals. 

(b) Wave lengths of Signals Known. — When the re- 
ceiving operator has been advised of the wave length of the 
signals he is to pick up, the process of tuning in is somewhat 
facilitated by the use of the table of wave lengths which is 
pasted in the cover of the box. 

The primary circuit of the set is first tuned, as explained 
above, with the switch on "AP," the secondary inductance on 
"60" and with maximum coupling. After the signals have 
been identified and the primary has been tuned to give maxi- 
mum loudness, the coupling is reduced as before and the switch 
M moved to T. The secondary inductance setting to be used 
is then given in the table. Thus, for a wave length of 280 
meters, the setting may be 30 or 45. It is best to use the higher 
value 45. The final secondary adjustment is then made as 
before by means of the secondary condenser. 

Use oi a Vacuum Tube Detector with the SCR-54 Set. 

It is sometimes desirable to use a vacuum tube detector 
in place of the crystal detector supplied with the set. In 



312 FIELD ARTILLERY MATERIEL. 

this case, the telephone stopping condenser of the set must be 
short circuited by inserting a dummy brass plug in the tele- 
phone jack. The crystal detector is then disconnected, and 
wires are connected from the detector binding posts of the 
set to the proper terminals of the vacuum tube detector set. 
The telephone receivers should not be plugged in, as before, 
in the jack of the set box, but must be connected to the proper 
terminals or jack of the vacuum tube detector box. 

Precautions, Sources of Trouble, Maintenance. 

In using this set, care should be taken to always keep it 
in as dry a place as possible. It should be kept in a clean con- 
tion, especially the operating panel, the contacts, binding 
posts, dial switch studs, and the telephone jacks. Oil or grease 
on these contacts will make the connections uncertain and 
unsteady and impair or even prevent the satisfactory opera- 
tion of the set. 

The set should be handled carefully to avoid warping 
the condenser plates or otherwise damaging the set. No 
foreign substance should be placed in the set box. Care should 
be taken that the telephone receiver cords do not get wet, for 
the resulting leakage of current through them would con- 
siderably decrease the strength of signals and introduce an 
annoying noise. The telephones do not require any adjust- 
ment, and the earpieces should always be kept screwed up 
tight. The telephone receiver should never be taken apart, 
since their adjustment at the factory is very accurate and per- 
manent. If it becomes necessary to remove the cord connec- 
tions from either the telephones or the plug, the wires must be 
connected as found, according to their different colors. This 
is important since otherwise the permanent magnets will be 
partially demagnetized and the efficiency of the telephone 
receivers will be seriously impaired. In packing the set for 
transportation the telephone head set receivers are placed 



SIGNAL EQUIPMENT. 313 

face to face so that the diaphragms will be protected and kept 
free of mud and dirt. The telephone cord is then wound 
around the head band in such a way as to hold the receivers 
together. The telephone plug is finally slipped inside the coil 
thus formed by the connection cord, and the entire set is care- 
fully placed in its compartment in the set box. Among the 
troubles most frequently encountered are those considered 
below. It may happen that the buzzer does not work. This 
may be due to a poor adjustment of the buzzer vibrator, or 
to a run down dry battery. If the radio does not work it may 
be because the crystal detector is not making contact with the 
sensitive spot. Readjust it with the aid of the buzzer. No 
sound in the receiver may be due to the fact that the tele- 
phone is not all the way in the jack, or that it is dirty. In 
this case see that the plug is clear in, or remove it and wipe 
it off with a clean cloth. Also, the dummy brass plug may be 
in the telephone jack. This would prevent operation entirely 
with the crystal detector. 

Scratching noises in the telepone may be the result of 
wet connection cord, or the connection at the plug or either 
telephone receiver may be loose. 

If the antenna or ground connections is loose, or if the 
ariel or lead in wire is grounded through a branch of a tree, 
or in some other way, the set will fail to operate. Make sure 
of good insulation all around. It sometimes happens that a 
wire will break inside the set box. This generally occurs to 
one of the wires connecting the secondary induction coils to 
the various taps to the secondary dial switch. One way to 
discover this fault is to turn the "Coupling" handle back and 
forth; the signals may then suddenly stop for a certain posi- 
tion of the handle, although they will be audible with the 
handle on either side of this position. Finally, a plate of 
one of the variable air condensers may become warped and 
short circuit the condenser. This is generally evidenced by the 



314 FIELD ARTILLERY MATERIEL. 

fact that the condeser, when varied over its whole range, does 
not change the loudness of the signals. In active service, the 
receiving sets are required to be in continuous working con- 
dition. To insure this, spare parts must be kept on hand at 
all times in order to replace defective parts with the least 
possible delay. Such spare parts should include spare crystals, 
telephones and telephone cords. Complete extra set should 
always be in stock at the central Radio supply station to pro- 
vide for replacement promptly when sets are destroyed. The 
sets in use should also be frequently tested to determine and 
readiness for an intensive and continuous activity. The 
condenser and inductance circuits should be tested to make 
sure that each part of each circuit is in perfect working con- 
dition. Testing of circuit parts may be simply done with a 
head phone and dry cell, a click through closed circuits, and 
the absence of a click through the condenser circuits, being the 
indication which should be noted. 



SMALL ARMS. 315 



CHAPTER XVI. 
SMALL ARMS. 

Notes on the Automatic Pistol, Cal. 45, Model 1911. 

The pistol is known as the Automatic Pistol, Cal. 45, 
Model 1911. By caliber is meant the caliber of the bore. All 
pistols used in the service are marked on the left side of the 
receiver, "United States Property," and on the right side with 
the serial number, which must be memorized by the person 
to whom the pistol is issued. 

It is important that every man have a thorough knowl- 
edge of the nomenclature, care and repair, method of assemb- 
ling and dismounting the pistol as well as its use and opera- 
tion. 

The principal parts of the pistol are the receiver, the barrel 
and the slide. 

To Dismount and Assemble the Pistol : — Press the maga- 
zine catch and remove the magazine. Press the plug inward, 
turn the barrel bushing to the right and by easing off on the 
spring let the plug and spring protrude gradually. Draw the 
slide to the rear until the small recess is opposite the thumb 
piece of the slide stop. Press gently against the end of the 
pin of the slide stop on the opposite side and remove the slide 
stop. This releases the link and allows the barrel and the 
slide with all its parts to be slid forward off the guide rails of 
the receiver. 

To Disassemble the Slide : — Remove the plug by turning 
it to the left and withdraw the recoil spring with its guide from 
the rear; or remove the recoil spring guide and withdraw the 
coil spring with its plug from the front. Turn the barrel 



316 FIELD ARTILLERY MATERIEL. 

bushing to the left and withdraw it forward from the slide. 
The barrel may now be withdrawn from the slide. To re- 
move the firing pin, press the rear end of the pin forward until 
it clears the firing pin stop. Then withdraw the stop down- 
ward from its seat, whereupon the firing pin, the firing pin 
spring, and the extractor are removed by withdrawing them 
to the rear. 

For ordinary cleaning, no further dismounting will be 
found necessary and no disassembling of the receiver should 
be permitted except by permission of an officer. When the 
interior of the pistol has been exposed to water, or when it is 
desired to make repairs, the receiver may be completely dis- 
mounted as follows: 

Cock the hammer, move the safety lock to a position 
half way between its upper and lower position. Press the end 
of the safety lock pin on the opposite side and withdraw the 
safety lock. Now lower the hammer by pressing the trigger. 
Push out the hammer pin and take out the hammer and 
strut. Next push out the housing pin. This may require a 
little extra pressure. It is the only pin pushed out by pressure 
from the left side of the receiver. The mainspring housing 
may then be withdrawn downward and the grip safety with- 
drawn to the rear. This exposes the sear spring, which is 
easily removed. By pushing out the sear pin, the sear and the 
disconnector are released. 

The main-spring housing is disassembled by compressing 
the main spring, pushing out the small main-spring cap pin, 
whereupon the main-spring cap, the main spring and the 
housing pin retainer will come out. The main spring may be 
easily compressed by using the pin of the slide stop. 

To remove the magazine catch, press the button inward. 
By means of a small screw driver or the short leaf of the sear 
spring, give the screw head of the magazine catch lock a quar- 




RECEIVER, BARREL AND SLIDE. 



SMALL ARMS. 317 

ter turn to the left and remove the magazine catch. The trig- 
ger can then be withdrawn to the rear. 

The hammer strut, a small nail or the long arm of the 
screw driver may be used to push out all pins except the main 
spring cap pin and the ejector pin. To remove these a tack or 
pin may be found necessary. 

To assemble the pistol proceed in the reverse order, 
except that the main spring housing should be left to project 
about one-eighth inch. Do not push the main-spring housing 
home and insert the housing pin until after the safety lock is 
replaced and the hammer lowered. 

The Operation of the Pistol. — The act of drawing back 
the slide in loading cocks the hammer, compresses the recoil 
spring, permitting the magazine follower to raise the upper 
cartridge into the path of the slide. Upon releasing the slide, 
the recoil spring forces the slide forward, carrying the first 
cartridge into the chamber of the barrel. As the slide ap- 
proaches its forward position, it encounters the rear end of 
the barrel, forcing the latter forward. Since the front of the 
barrel pivots in the barrel bushing and the rear end is free to 
swing upward on the link, the rear end of the barrel is raised, 
causing the locking ribs on the outside of the barrel and the 
inside of the slide to engage, thus positively locking the barrel 
and the slide together. The joint forward movement of the 
barrel and the slide (about three-eights of an inch) is stopped 
when the barrel lug encounters the pin of the slide stop. 

The pistol is then ready for firing. When the hammer 
is cocked, the hammer strut moves downward, compressing 
the main spring. The sear, under the action of the long leaf 
of the sear spring, engages its nose in the notch of the hammer. 
Upon pulling the trigger and pressing on the grip safety, the 
sear is moved, thus releasing the hammer. The latter then 
strikes the firing pin which transmits the blow to the primer 



318 FIELD ARTILLERY MATERIEL. 

of the cartridge. The explosion of the cartridge generates 
the necessary gas pressure to force the bullet through the 
barrel, the initial muzzle velocity being about 800 ft. per 
second. The pressure exerted to the rear against the face of 
the slide carries the latter and the barrel to the rear together. 
But due to the link attachment, the barrel is almost im- 
mediately swung down and unlocked from the slide, leaving 
the slide to continue its movement to the rear, thus opening 
the breech, cocking the hammer, extracting and ejecting the 
empty cartridge and compressing the recoil spring. When the 
slide reaches its rearmost position the magazine follower 
raises another cartridge into the path of the slide. This 
cartridge is then forced into the barrel by the forward move- 
ment of the slide as before described. 

Although it might be supposed that the downward swing- 
ing of the barrel would affect the accuracy of the fire, this is 
not the case. The bullet has gained its maximum velocity 
and passed out of the muzzle before the unlocking movement 
between the barrel and slide commences. 

When the magazine has been emptied the magazine 
follower is free to press against the projection on the slide 
stop, thus forcing the slide stop into the front recess of the 
slide, thereby locking the slide in the open position and re- 
minding the person firing that the empty magazine must be 
replaced before firing can be continued. 

Interesting Facts about the Pistol. 

(a) Weight 2\ pounds. Trigger pull, about 7 pounds. 

(b) Rifling, 6 grooves with left-hand twist. The drift 

due to the rifling is therefore to the left, but this is more than 

neutralized by the pull of the trigger when the pistol is fired 

from the right hand. 

(c) For ranges up to 75 yards the trajectory is very flat 
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SMALL ARMS. 319 

(d) Beyond 250 yards the trajectory is very curved and 
the drift becomes considerable. Firing is therefore very in- 
accurate. 

(e) To hit a target at ranges over 75 yards it will be 
necessary to lay on a displaced point above and to the right of 
target for ranges approximately as follows : 





Vertical 


Lateral 


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Displacement. 


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100 


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i yard 


150 


lj yards 


i yard 


200 


3 yards 


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250 


5 yards 


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(f ) The striking energy of the bullet is sufficiently great 
to surely disable a man by causing a dangerous wound at all 
ranges up to 500 yards. 

(g) The pistol has been fired by experts at 25 yards, 
aimed fire, at the rate of 21 shots (3 magazines) in 30 seconds. 
Such rapidity is, however, not necessary or desirable in service 
firing. Accuracy is always the first consideration. 

Precautions. 

1. Whenever the pistol is taken out of or returned to the 
arm rack, also both before and after drill or other exercises 
with the pistol, remove the magazine and see that it is empty. 
Then draw back the slide which will eject any cartridge in the 
chamber. Finally look through the bore to see that the pistol 
is unloaded and the bore not obstructed by a plug or wad. 
Replace all parts, come to raise pistol and low^er hammer. 

2. Never place the trigger finger within the trigger guard 
until it is intended to fire and the pistol pointed toward the 
target. 

3. Do not carry the pistol in the holster with the ham- 
mer cocked and the safety lock on, except in an emergency. 

T. B.— 21 



320 FIELD ARTILLERY MATERIEL. 

4. Always press the trigger with the forefinger. 

5. After each shot relieve the pressure on the trigger so 
that the sear may re-engage. 

6. When inserting the magazine be sure that it engages 
the magazine catch. Never insert the magazine by striking 
it smartly; always apply a continuous push. 

7. The pistol must be kept clean, free from rust and 
properly oiled. 

8. Never disassemble the receiver except by permission 
of a officer. 

9. In disassembling the receiver be sure that (a) the 
disconnector and sear are properly assembled; (b) that the 
hammer is not snapped when the pistol is partially assembled ; 
(c) that the stocks are not removed; (d) that no hammer is 
used in either assembling or disassembling. 

Care and Cleaning of the Automatic Pistol. 

In cleaning the barrel of the automatic pistol after firing 
proceed as follows: Swab out the bore with soda solution to 
remove powder fouling. Remove and dry with a couple of 
patches. Examine to see that no patches of metal fouling 
are in evidence, then swab out with the swabbing solution— 
a dilute metal-fouling solution. The amount of swabbing re- 
quired with the swabbing solution can be determined only by 
experience assisted by the color of the flannel patches. Nor- 
mally a couple of minutes' work is sufficient. Dry thoroughly 
and oil with sperm oil. 

The proper method of oiling a barrel is as follows: Wipe 
the cleaning rod dry; select a clean patch and thoroughly 
saturate it with sperm or light slushing oil, being sure that the 
oil has penetrated the patch; scrub the bore with the patch, 
finally drawing the patch smoothly from the muzzle to the 
breech, allowing the cleaning rod to turn with the rifling. The 



SMALL ARMS. 321 

bore will be found now to be smooth and bright so that any 
subsequent rust or sweating can be easily detected by inspec- 
tion. 

The principles as outlined above apply equally well for 
the care of the barrel of the sub-calibre cartridge. 

MACHINE GUNS AND AUTOMATIC RIFLES AS 
EMPLOYED BY THE ARTILLERY. 

The field artillery employs machine guns and automatic 
rifles only defensively, either against hostile aircraft, or against 
enemy infantry in case of a break-through. For this reason 
the tactical use of these weapons by the artillery is consider- 
ably different from that by the infantry, and the dispositions 
that must be made are adapted to particular needs. 

The field artillery must defend itself: 

(a) On the march. 

(b) In position. 

(c) At the echelon (horse-lines). 

Defense on the March. 
1. Machine Gun. 

Machine guns may be used on the march in case of sur- 
prise attack or against low-flying aeroplanes. Fire on roads 
and convoys from low-flying aeroplanes has been developed 
to such an extent that it is imperative at all times for a column 
to be prepared to defend itself against such attacks. 

1. When a battery is in the advanced zone, one machine 
gun is mounted on a special mount on the second caisson of the 
fifth section. This gun is kept ready for fire at all times, the 
loaded belt if it is a Browning, being kept in the loaded posi- 
tion. About 500 rounds Cal. 30 ammunition are carried on 
the caisson. The machine gunner in charge of the gun marches 
with the 5th section. 



322 FIELD ARTILLERY MATERIEL. 

A mechanic can very easily modify the special mount for 
the Browning, for use against aircraft, so that it also will be 
adaptable for use on the caisson. 

One gun is attached to the fifth section, so that on sub- 
division of the battery for action, the other gun will be with the 
Combat Train or echelon, being carried in the battery wagon 
or the park wagon. 

The second gun may be carried stored in the battery 
wagon or on escort wagon. In position warfare the firing bat- 
tery goes into position usually at night. The escort wagon 
then goes up with tools, officers' rolls, etc. and the machine 
gun with its special mount, the regular tripod, and about 
2000 rounds of ammunition. If not carried as stated, provi- 
sion must be made for carrying the gun with the firing battery. 

2. Automatic Rifles. 

The automatic rifles are assigned one to each section. 

All eight automatic rifles should be in readiness for instant 
use when on the march. They should be evenly distributed 
throughout the battery, and handled by men who have had 
special training. At least two magazines per gun (40 rounds) 
should be instantly available. While it is difficult to bring 
down a plane with a machine gun or rifle, a well directed 
fire will limit the action of hostile planes. 

It should be borne in mind that often when in the ad- 
vanced zone friendly aeroplanes are detailed to guard a bat- 
tery on the march. Great care must be taken to make no 
mistakes in identifying aeroplanes. Never shoot at a ship un- 
less the distinctive markings on the wings are clearly distin- 
guished and identified. Upon subdivision for action, the au- 
tomatic rifles go with the section to which assigned. This, of 
course, may be varied according to the situation. 



SMALL ARMS. 323 



(B.) Defense of the Position. 

The machine gun emplacement should be carefully 
selected and constructed. The first consideration is a good 
field of fire; the second is good concealment. 

Usually it is placed on a flank of the battery. Situated 
on the flank of the battery, a greater field of fire is obtained 
for the gun. Moreover when firing against hostile airplanes, 
the position of the battery will not necessarily be disclosed. 
In case the battery is shelled, the position of the machine gun 
on the flank renders it less liable to be hit. 

The emplacement for a machine gun at a battery position 
differs from those generaly built by the infantry in that it is 
designed primarily for anti-aircraft shooting. 

There can be no overhead cover, all protection being pro- 
vided by well constructed concealment. Camouflage must be 
arranged for and so placed that it can be instantly thrown 
aside for firing. 

The plans for close defense of the battery should include 
the assignment of positions and sectors of fire for the automatic 
rifles. 

The methods of fire and the technical points involved, in 
firing against hostile airplanes, will be considered elsewhere. 
A sentinel equipped with a pair of field glasses must be on 
duty in the emplacement at all times. The members of the 
machine gun squad are detailed for this duty by roster. 

Types of Anti-Aircraft Mounts. 

The Ordnance Department furnishes no anti-aircraft 
mount, but improvised mounts can be easily made. 

BROWNING MACHINE GUN— MODEL 1917. 

The Browning Machine Gun, Model 1917, is water-cooled 
and is chambered for calibre .30 U. S. Standard Rifle Ammuni- 



324 FIELD ARTILLERY MATERIEL. 

tion. The gun is classed as a heavy water-cooled gun, recoil 
operative and belt fed. 

The water holds about 7 pints of water and is perfectly 
smooth on its interior. The steam escape tube is in the top 
of the water jacket, and is made up of two tubes. They slide 
one upon the other, the outer one being a little shorter than 
the inner one. This allows the outer tube to slide toward 
either end and uncover the highest steam escape hole. The 
force of recoil is utilized to perform the various mechanical 
operations of feeding in the cartridges, loading, cocking, 
firing the gun and ejecting the empty shells through the bottom. 

The several cams of the gun make each moving part of 
the gun have a positive motion. 

The feed belt is made of woven fabric and has no metal 
parts to cause feed jams and to add extra weight to the piece. 
Also the metallic disintegrating links are used with the aero- 
plane gun. The fibre belt usually contains from 250 to 500 
rounds. The metallic belts can be made to contain any 
number of rounds desired. 

The gun has very few screws and springs. It is composed 
of about forty parts which may be taken down in the field. 
There are a few parts which can be assembled incorrectly and 
it cannot be determined that they are so assembled until the 
gun is ready to be put into action. At this point the gunner 
will find that the gun will not operate, therefore great care 
should and must be used in the study of a quick and positive 
assembling. 

The weight of this gun is about 30 pounds without water. 
This weight makes it necessary to use the gun on a tripod or 
other suitable mount. 

General Data. 

Weight of the gun — no water 30 lbs. 

Weight of the gun filled 36.75 lbs. 



SMALL ARMS. 325 

Weight of the belt, 250 rounds 15.25 lbs. 

Length of the barrel 24 in. 

Weight of the belt, empty 7.5 oz. 

Sight graduated to 2800 meters. 

Rate of fire (shots per minute) 400-525. 

Aimed shots per minuts 120. 

Calibre of bore 30 in. 

Weight of bullet 150 grs. 

Weight of cartridge 394 grs. 

Chamber pressure lbs. per sq. in 47,000-50,000. 

Muzzle velocity (ft. per sec, theoretical) 2700. 

THE BROWNING AUTOMATIC RIFLE. 
General Description. 

The Browning Automatic Rifle, Model of 1918, is cham- 
bered for the United States standard ammunition. This 
rifle is classified as a light automatic rifle commonly referred 
to as the "Light Browning." It has been fired 148 shots per 
minute, semi-automatic, while marching, and 110 shots per 
minute, semi-automatic, from the shoulder while in prone posi- 
tion. The rates of fire, which give the best results are from 80 
to 100 rounds per minute, semi-automatic marching fire and 
50 to 60 shots per minute, semi-automatic aimed fire. 

Operation. 

Expanding powder gases furnish the energy for the opera- 
tion of the gun. After the gun is fired and the bullet has 
passed the gas port in the barrel, the live powder gases expand 
through the gas port into the gas cylinder and impinge against 
the head of the piston. This sudden blow forces the piston to 
the rear, compressing the recoil spring and storing up energy 
for the return movement. The various lugs and cams actuate 
the feeding, firing, extraction and ejection, and also control the 



326 FIELD ARTILLERY MATERIEL. 

operation of the gun. The feeding is accomplished through 
a magazine holding 20 or 40 rounds in double rows. It is held 
between the sides of the receiver, in front of the trigger guard. 
This magazine is composed of a rectangular tube and a round 
wire spring wound to fit the tube. Also there is a bottom plate 
which slide in the bottom and forms the rest for the spring. 
On top of the spring is a follower, which forces the cartridge 
up against the lips of the magazine tube and which holds it in 
place until stripped out by the lug on the bottom of the bolt. 
The automatic action of this gun is not disturbed by holding 
it in any position whatever. The magazine can be inserted 
while the mechanism of the gun is in either the cocked or for- 
ward position. 

All parts of the gun are designed so as to impose a mini- 
mum of shock and strain upon them. They are also made 
strong enough to hold up under the maximum amount of work 
that they can be made to perform. There are few parts that 
can be assembled incorrectly but the gun will not function 
unless these parts are assembled correctly. The dismounting 
and assembling of the rifle can be accomplished without the 
aid of a single tool unless the barrel and gas cylinder are re- 
moved which necessitates the use of a special spanner wrench 
provided in the kit. 

General Data. 

Weight of gun 15 lbs. 8 oz. 

Weight of Magazine, empty (20 rounds). 7 oz. 

Weight of Magazine, filled (20 rounds)... 1 lb. 7 oz. 

Length of barrel 24 inches. 

Sights graduated up to 1,600 yards. 

Calibre bore 0.30 inch. 

Gas port form muzzle 6 inches. 

Rate of fire 500 shots p'm. 

Aimed shots per minute, semi-automatic. 60 shots p'm. 



SMALL ARMS. 327 

Weight of bullet 150 grains. 

Weight of Powder 47 grains 

Weight of Cartridge (total) 395.5 grains. 

Chamber pressure, pounds per square 

inch 47,000 to 50,000. 

Muzzle velocity 2,682 ft. p's. 

Habitual type of fire semi-automatic. 

Cooling System. 

It has no special cooling system or device, the barrel 
merely being exposed to the air and the hand of the firer being 
protected on the under side of the barrel by a large wooden 
forearm. Since the barrel soon becomes very hot, care must 
be taken to avoid touching it during firing or for five or ten 
minutes thereafter. 



328 FIELD ARTILLERY MATERIEL. 



CHAPTER XVII. 

MOTORS. 

RECONNAISSANCE CAR. 

The reconnaissance car as supplied to regiments of 155- 
mm howitzers, motorized, consists of two units: Reconnais- 
sance body, model 1918; 1-ton truck chassis, White, T E B-0. 

Further information concerning these units will be found 
in Ordnance Handbooks " Reconnaissance Body, Model 1918;" 
"1-Ton Truck Chassis White, T E B-0" (No. 1972). 

Weights and Dimensions. 

Rated load capacity (body allowance plus 

normal load) 1 ton-1,040 kg. 

Body weight allowance 1,500 lb.-862 kg. 

Chassis only 3,850 lb.-l,750 kg. 

Oil, water and gasoline 190 lb. -86. 5 kg. 

Chains 69 lb.-31.5 kg. 

Tool kit 37 lb.-16.8 kg. 

Chassis weight on front tires (without 

load) 54%. 

Chassis weight on rear tires (without 

load) 46%. 

Gross weight (capacity load) 7,150 lb. -3, 250 kg. 

Load weight on front tries 0.78%. 

Load weight on rear tires 99.22%. 

Gross weight on front tires 27%. 

Gross weight on rear tires 73%. 

Overall length of chassis (without body). 205 in.-5,220-mm. 

Overall width of chassis (at widest part). . 61 in.-l,550-mm. 



MOTORS. 329 

Chassis wheel base 140 in.-3,560-mm. 

Permissible loading space back of driver's 

seat 97 in.-2, 470-mm. 

Width of frame (outside dimension, wid- 
est part) 34 in.-865-mm. 

Height of rear end of frame from ground 

(empty) 33.75 in.-856-mm. 

Diameter of turning circle (right) 60 ft. -18. 3 meters 

(left) 45ft.-13.7 meters. 

Tread of wheels 56 in.-l,422-mm. 

Road clearance under front axle (lowest 

point) 10.75 in.-273-mm. 

Road clearance under rear axle (lowest 

point) 10 in.-254-mm. 

Length of reconnaissance body, overall. . . 160 in.-4,072-mm. 

Width of body 59.875 in.- 

1,522-mm. 

Height of body, overall (including top). . 62.125 in.- 

1,580-mm. 

Weight of body (without equipment) .... 1,180 lbs. -536 kg. 

Brief Description. 

The reconnaissance car is provided with a special steel 
body, mounted on a 1-ton truck chassis, White Model TEB-0. 
Four seats are built into the body. The two front seats are 
placed back to back. The two rear seats have a space be- 
tween them of about 2 feet and are also placed back to back. 
There is a compartment between the two pairs of seats. 
The floor boards at the back end are extended to form a foot 
rest for the rear seat. The car is protected by a canopy top 
and roll curtains. A full set of tools is carried on the car. 
Also five chests are provided in which are carried all the special 
equipment assigned to the car. One chest slides into the body 
compartment under the rear front seat, one into the compart- 



330 FIELD ARTILLERY MATERIEL. 

ment between the rear seats, and the other three under the 
rear seat. 

The chassis used is similar to that used with the Staff 
Observation car on page 95. A complete description and 
directions for care, operation, and maintenance are contained 
in the "Handbook of the Reconnaissance Car, Model of 1918." 
Ordnance pamphlet No. 1972. 

ARTILLERY TRACTOR, 5-TON MODEL OF 1917. 

Weights and Dimensions. 

Overall length (armored) 133.5 in.-3,400-mm. 

Overall width 63 in.-l,605-mm. 

Height (armored, to top of muffler). . 72.5 in.-l,845-mm. 

Length of ground contact 91 in.-2,315-mm. 

Ground clearance 11 in.-280-mm. 

Weight (complete with full equip- 
ment) 9,200 lbs.-4,180 kg. 

Ground pressure (9 and 11 inch 

treads) 5.G-4.5 per sq. in.- 

0.394-0.316 kg. per 

sqcm. 

Weight of each track 545 lbs. -548 kg. 

Weight of each track shoe (9-in.) ... 12 lbs. -5.45 kg. 

Width of track shoes 9-11 in.-299-280-mm. 

Tread of tracks (center to center of 

tracks) 48.875 in.-l,243-mm. 

Diameter of turning circle (overall 

clearance) 176 in.-4,425-mm. 

Engine, number of cylinders 4 

Bore 4.75 in.-220.8-mm. 

Stroke 6 in.-152.5-mm. 

Horsepower at 1,200 revolutions 

per-min 56. 



MOTORS. 331 

Oil reservoir capacity 3.25 U. S. Gal-12.22 

liters. 

Road speed-gear used (per hour) 
Low speed at 1,200 rev. per min- 
ute of engine 1.94 miles-3.12 kilos. 

Direct speed at 1,200 rev. per 

minute of engine 3.92 miles-6.31 kilos. 

High speed at 1,200 rev. per 

minute of engine 7.37 miles-11.85 kilos. 

Reverse speed at 1,200 rev. per 

minute of engine 1.41 miles-2.27 kilos. 

Capacity of main gasoline tanks 

(two) combined 24 U. S. Gal.-90.5 liters 

Capacity of auxiliary tank under 

armor 10 U. S. Gal.-37.85 

liters. 

Capacity of transmission case 3 U. S. Gal. -11. 3 liters 

Capacity of track oiler tank 2.5 U. S. Gal.-9.43 

liters. 

Brief D escription. 

The 5-ton artillery tractor, Model 1917, is a self-pro- 
pelled road vehicle of the " track laying" type; that is, the 
power is transmitted to the ground through a flexible endless 
chain which acts as a track and is composed of steel links 
and shoes cast integral and connected by hardened steelpins 
The advantage of this type of tractor as compared with the 
usual type of wheel tractor or truck, is its ability, due to very 
low unit ground pressure, to negotiate very soft and uneven 
surfaces, impassable to the usual type of self-propelled vehicle 
except under the most extreme difficulties. 

The general design and construction of the 5-ton tractor 
does not differ materially from that of the modern truck except 
in the method of transmitting the power from the transmission 



332 FIELD ARTILLERY MATERIEL. 

unit to the ground. It is used solely as a power vehicle for 
hauling howitzers carriages and caissons. Each carriage and 
carriage limber are drawn by one tractor and each pair of 
caissons are drawn by one tractor. 

A complete description and instructions for care, main- 
tenance, and operation are contained in the "Handbook of 
5-Ton Artillery Tractor, Model of 1917." (No. 1996). 

Outline Specifications. 

Engine. — Four cylinder, four cycle, valve-in-the-head 
type. Bore 4.74". Stroke, 6". Cylinder case in pairs. 
Horsepower 56 at 1,200 revolutions per minute. 

Radiator. — Honey-comb tubular type. Eight separate 
headers. 

Ignition. — Eisemann, Model G-4, high tension magneto 
with automatic impulse starter. 

Carbureter. — Model A Schebler carbureter with Stewart 
vacuum feed system; 1.5". 

Governor. — Centrifugal flyball type mounted on special 
shaft and driven off camshaft gear. 

Master Clutch. — Dry plate multiple disk type. 

Transmission. — Selective sliding gear type. Three speeds 
forward, one reverse. Direct drive on second. Stepped up 
on high. 

Drive. — From transmission through bevel gears to steer- 
ing clutch shaft through steering clutches to spur pinions, 
which mesh with intermediate spur gears, thence through out- 
side gears, encased, to sprocket drive sleeve and drive sproc- 
kets. 

Steering Clutches. — Two used of dry plate multiple disk 
type. 



MOTORS. 333 

Steering. — By means of steering clutches operated from 
hand steering device and brake bands operated by foot 
pedals, which act on outside of steering clutch drums. 

Control. — Steering gear located on the right hand side. 
Change gear, master clutch operating lever, and brake lever, 
left of steering gear, left to right respectively. Spark and 
throttle levers operate on sector clamped to steering column. 
Steering clutch pedals right and left at bottom of, and in 
front of steering column. 

Brakes. — One set. External contracting type. Ray- 
bestos, or equal, lined. Operate on steering clutch housings. 

Gasoline Tank. — Terneplate tanks. Two independent 
duplicate tanks each of 12 gallon capacity. Auxiliary terne- 
plate tank under armor, 10-gallon capacity. 

Main Frame. — Cast in one piece-open hearth steel. 

Roller Frames. — Four frames steel channel, joined by 
oscillating shaft. Two frames right and left front. Two 
frames right and left rear. 

Truck Rollers. — Six on each side of tractor, fitted with 
roller bearings, turned on steel gudgeons, flanked to follow 
track rail. 

Track. — Made up of malleable iron track shoes with 
track links. Integral, fitted with space blocks, and 1.25" 
pins. 

Track Drive Sprockets. — Two. Teeth mesh with open- 
ing in tracks. 

Blank Sprockets. — Two. Fitted with roller bearings 
which turn on steel gudgeons. Used to adjust track tension. 

Track Supporting Rollers.— Four on each side of trac- 
tor, two mounted on brackets attached to front roller frame 
channel, and two in the rear mounted on spring bracket 
which is bolted to main frame. 



334 FIELD ARTILLERY MATERIEL. 

Springs. — Four double coil springs at rear, two on each 
side between rear roller frame and bracket on main frame 
and four — two on each side of equalizing bar at front. 

Equalizing Bar. — Spring supported on front roller frame 
sections. 

AMMUNITION TRUCK. 

The ammunition truck supplied to regiments of 155-mm 
howitzers, model of 1918, motorized, consists of two units: 
Ammunition truck body, model of 1918; 2-ton truck chassis, 
Nash model 4017-A and 4017-L. 

Further information concerning those units will be found 
in the Ordnance Handbooks. "Ammunition truck body, 
model of 1918" (No. 2002); "2-ton truck chassis, Nash 
model 4017-A and 4017-L." 

Weights and Dimensions. 

Weight of body 1,200 pounds. 

Overall length of body 120 inches. 

Overall width of body 56 inches. • 

Overall height of body 54 inches. 

Width of floor (inside) 43 inches. 

Length of floor (inside) 114 inches. 

Height of sides (inside) 36 inches. 

Brief Description of Ammunition Truck Body. 

The ammunition truck body, model of 1918, consists of 
a box-type steel body opening only at its rear end. The body 
is designed to accommodate original packing cases of any 
type of ammunition. When this vehicle is used near the 
front lines all four sides and its floor are lined with detachable 
heavy cocoa matting to prevent undue noise. A tarpaulin 
cover attaches to the body, and so protects its contents. 



MOTORS. 335 

In addition to the designation of ' 'ammunition truck," 
as explained the ammunition body with various loads is desig- 
nated when mounted on chassis models as follows: "Wireless," 
"Telephone," "Tanks," "Personnel," "Baggage," and "Ra- 
tion." 

The chassis and bodies for the above are identical for 
all purposes. The differences in chassis and body equipment 
and the load carried when the truck is used for different pur- 
poses are noted under tables of equipment on page 161. All 
of the above bodies are mounted on a 2-ton Nash truck chassis. 

Outline Specifications of all 2-Ton Chassis, Nash Models # 

Rated load capacity 4,000 lb.-l,820 kg. 

Body weight allowance 1,200 lb. -546 kg. 

Weight of chassis only 6,700 lb.-3.030 kg. 

Maximum gross weight (including 

chassis, body and load) 11,900 lb.-5,420 kg. 

Percentage of chassis weight on front tires (with- 
out load) . . 66.66% 

Percentage of chassis weight on rear tires (without 

load) 33.33% 

Percentage of load weight on front tires 30.00% 

Percentage of load weight on rear tires 70 . 00% 

Percentage of gross weight on front tires 45 . 00% 

Percentage of gross weight on rear tires 55.00% 

Overall length of chassis (without 

body) 202.50 inches-5,100-mm. 

Overall width of chassis (at widest 

part) 78.50 inches- 1,950-mm. 

Chassis wheelbase 124.00 inches-3,155-mm. 

Length of frame back of drivers 

seat 117.13 inches-2,980-mm. 

Width of frame (outside dimen- 
sions) ,......,..,..,,...,,...- 38.13 inches-968-mm, 



336 FIELD ARTILLERY MATERIEL. 

Height of rear end of frame from 

ground loaded 35.50 inches-890-mm. 

Height of rear end of frame from 

ground unloaded 38.50 inches-980-mm. 

Diameter of turning circle 50.00 feet-15.25 meters. 

Tread of front wheels GO. 50 inches- 1,540-mm. 

Tread of rear wheels 60.50 inches-l,540-mm. 

Road clearance under front axle 

(lowest point) 14.75 inches-374-mm. 

Road clearance under rear axle 

(lowest point) 14.75 inches-374-mm. 

Brief Description, Models 4017-A, 4017-L, and 4017-F. 

The chassis of all these models is of 124-inch wheel base 
and is fitted with a Buda model H-U four-cylinder engine, 
dry disk clutch, four speed transmission, and a drive to all 
four wheels through shafts and internal gearing. Although 
the greater number of units in all three chassis are alike, there 
are certain structural differences which exist, mainly in the 
model 4017-F chassis as against the other two. The 4017-F 
is a two wheel steer chassis, while the others have four wheel 
steering. All of them use four wheel drive and braking. 
The models 4017-A and 4017-L are fundamentally the same, 
differing only in certin details of equipment. Model 4017-L 
has an acetylene generator and searchlight, and oil side and 
tail lamps, both speedometer and odometer and an im- 
pulse starter on the magneto shaft, while the 4017-A has no 
impulse starter, uses a Bijur electric generator, storage bat- 
tery and electric lamps, and is fitted with an odometer only 
Aside from the two wheel steering and the necessary changes 
brought about by it, models 4017-F and 4017-L are practically 
the same, though a few slight differences exist in the dash, 
the brake cross shaft and rods and the wheel universals as 
described in detail in the Ordnance Handbook No. 1999. 



MOTORS. 337 

The engine is a standard design L-head, Buda model 
H-U using force-feed lubrication, pump cooling, and fitted 
with a Stromberg carburetor feeding through cored passages 
in the cylinder block, and Eisemann magneto, and on the 
model 4017-A only, with a Bijur generator. 

The clutch is of the dry plate type and the drive from it 
is through an open two-joint propeller shaft to a four speed 
sliding jaw-clutch type transmission. From the latter extend 
two-joint propeller shafts, one forward and one rearward, to 
internal gear-drive axles. The live member has exposed 
axle shafts extending from it, and the ends of these shafts 
are fitted with a universal joint and a spur pinion, the latter 
meshing with an internal gear bolted to a disk steel wheel. 
All the wheels are interchangeable and are all driving and 
steering wheels in models 4017-A and 4017-L, while in the 
model 4017-F only the front wheels steer. 

A complete description of the 2- ton truck chassis, models 
4017-A, 4017-L, and 4017-F, with instructions for care, main- 
tenance, and operation, is given in the "Handbook of the 2- 
ton Chassis Nash Models 4017-A, 4017-L and 4017-F," Ord- 
nance Pamphlet No. 1999. 

HOW TO DRIVE. 

Before starting an engine the driver should see that the 
gear shift lever is in neutral position and that the emergency 
brakes are set. The spark lever should be set at the proper 
position. If battery ignition is used it is best to have the 
lever in full retard position, as the spark will occur no matter 
how slow the engine is cranked. If magneto ignition is 
used the lever should be advanced slightly as a hotter spark 
is obtained in the advanced position than in the retarded. 
There is less probability of a kick back when starting on 
magneto since it is necessary to turn the engine at a fairly 



338 FIELD ARTILLERY MATERIEL. 

high rate of speed, approximately 100 R. P. M. to generate 
sufficient current to produce a spark. 

The position of the throttle hand control should be set 
so that the throttle will be slightly open. In case the car- 
buretor is equipped with an air-choking device this should be 
closed to cause a rich mixture for starting. 

The ignition switch should be turned on and the engine 
cranked by pulling up quickly on the crank handle a quarter 
turn at a time. If an electric cranking motor is provided 
depress the starting button and advance the spark. If 
magneto ignition is used it is best to spin the engine. Crank 
the engine with the left hand if possible and stand in such a 
position that if the engine should kick back the crank will 
not cause injury. 

After the engine has started release the choke on the 
carburetor advance the spark and close the throttle to a posi- 
tion which will prevent racing. If a special dash adjustment 
is provided for regulating the mixture allow this to remain 
in a position to cause a rich mixture until the engine warms 
up. 

To Start the Car. 

Allow the engine to warm up sufficiently to overcome 
missing and to run smoothly. When satisfied that the engine 
is running properly release the emergency brake. In case 
the car is on a grade apply the foot brake to prevent the car 
from moving. Press the clutch pedal all the way down and 
move the gear shift lever to first speed position. The clutch 
should be allowed to engage gradually and at the same time 
the throttle should be opened sufficiently to prevent stalling, 
but not cause racing of the engine. If the foot, brake has been 
employed it should be released as the clutch is engaged. 
After the clutch has been fully engaged the throttle should be 
opened sufficiently to accelerate the car to change to the next 



MOTORS. 339 

higher speed. The throttle should be controlled by the foot 
accelerator pedal. Once the car is in motion the driver must 
at all times keep his eyes on the road in the direction in which 
the car is moving or about to move when changing direction. 

To Shift Gears (Increasing Speed). 

Before starting a driver should practice moving the gear 
shift lever to the different positions and getting his feet and 
hands accustomed to the location of the foot pedals and hand 
levers. Then it will not be necessary to look away from the 
road in order to shift gears or in any other way to control 
the operation of the car. To change gears the clutch pedal 
should be depressed (it may not be necessary to push it all 
the way down against the floor boards) and the foot removed 
from the accelerator pedal at the same time. Move the gear 
shift lever from first to neutral position, pausing if necessary 
and then move to second speed position. Engage the clutch 
immediately and open the throttle with either hand or foot 
control as soon as the clutch is engaged. The process of 
changing from second to third or third to fourth is identical. 
Bear in mind that before each change is made the speed of the 
car should be accelerated. Care should be taken when chang- 
ing from lower to a higher speed that the car is moving at 
a sufficient rate of speed so that an undue strain will not be 
put on the engine. Practice alone in driving the particular 
apparatus will acquaint the driver with the necessary speed 
required to change from one gear ratio to another. 

To Shift Gears (Decreasing Speed). 

When it is desired to change from a higher to a lower gear 
ratio release the clutch and allow the hand or foot throttle 
control to remain open far enough so that the engine will 
speed up. Move the gear shift lever to the neutral position 



340 FIELD ARTILLERY MATERIEL. 

and again engage the clutch for an instant. Release the clutch 
immediately and quickly move the gear shift lever from 
neutral to the next lower speed position and engage the clutch 
immediately, opening the throttle by hand or foot control. 

Another method of shifting to a lower gear ratio is to 
leave the throttle open and release the clutch just enough to 
allow it to slip and the engine to speed up. The gear shift 
lever should then be moved through neutral directly to the 
next lower speed position and the clutch engaged. This 
method does not require as much practice but is objectionable 
since it wears or burns the clutch facing. 

To Stop the Car. 

To stop the car, the throttle should be closed, the clutch 
released, and the brakes applied, all being performed at the 
same time. The amount of pressure applied at the brake 
pedal depends upon the distance in which the driver desires 
to stop the car. Before allowing the clutch to engage after 
the car has stopped, move the gear shift lever to the neutral 
position. If the car is to stand apply the emergency brakes. 
If the engine is to be stopped speed it up by opening the 
throttle just before turning the ignition switch to the posi- 
tion "off." If the weather is cold use the choke when stop- 
ping the engine or set dash adjustment to give a rich mixture. 
This will make starting easier if the engine is started in a 
reasonable length of time. 

Driving Suggestions. 

In operating a car it is always best to alternate the serv- 
ice and emergency brakes rather than to use one continuously, 
to equalize the wear on them. When approaching a very 
steep down grade it is safest to move the gear shift lever to a 
lower speed position, closing the throttle and permitting the 



MOTORS. 341 

car to drive the engine. When the grade is not excessively 
steep the engine can be used as a brake with the position of the 
gear shift lever remaining unchanged. This will save the 
brakes and tend to cool the engine. The brakes should never 
be applied suddenly enough to slide the driving wheels except 
in cases of emergency. When a stop is to be made apply the 
brakes soon enough so that the motion of the car will be grad- 
ually diminished and brought to a stop at the point desired. 

To avoid accidents on the road all rules and regulations 
governing the driving of motor vehicles on the road should be 
observed. When turning corners or approaching cross-roads 
warning should be given to avoid collision with other vehicles 
which may be hidden from the view of the driver. Before 
backing the machine the driver should be sure that the road 
is clear. In manipulating the car the front wheels should 
never be turned by moving the steering wheel when the car 
is not in motion. This puts undue strain on the steering 
apparatus and will cause lost motion in the steering gear. 
If it becomes necessary to move the front wheels of a car while 
it is standing still, they should be moved by applying force 
not only to the steering wheel but also by pulling the front 
wheels around. 

When a car skids, the tendency is for an inexperienced 
driver to apply the brakes and turn the front wheels in the 
opposite direction to that in which he is skidding. This 
should not be done as it only accentuates the skidding and the 
car may be ditched or skid into another vehicle or the curb- 
ing. When the machine starts to skid turn the steering 
wheel in the direction in which the car is skidding and par- 
tially close the throttle but not entirely, or it will have the 
same effect as applying the brakes. When the car straightens 
out the power may again be applied graually, and the machine 
brought back to the center of the road. When skidding on 
narrow roads it is best to apply the power and steer to the 



342 FIELD ARTILLERY MATERIEL. 

center of the road. This will aggravate the skid for a mo- 
ment but brings the machine around at an angle with the 
front wheels in the center of the road. The momentum of the 
car will cause the rear wheels to climb back onto the road 
agan. 

ENGINE TROUBLES. 

If the machine will not start the trouble, can only be 
located by a systematic search. It is always best to look 
over the ignition system first, then see if there is any gasoline 
in the carburetor. It will often take some time to find the 
trouble. However, if the engine once starts there is little 
difficulty in locating the trouble as there will always be an 
indication which should point to the source of trouble. The 
great difficulty with inexperienced drivers is that they do 
not reason out the matter carefully before attempting to 
remedy it. Also an inexperienced man usually looks for 
trouble in the same place no matter what the indication may 
be. Nearly all difficulties arise from one of three sources, 
ignition, carburetion, or engine. These are outlined in the 
following table. The trouble is located by the trouble it 
gi\ cs the driver. 

I. Engine misses: 

A. Ignition. 

1. Plugs. 

a. Short circuit. 

b. Broken porcelain. 

c. Too large a gap. 

2. Cable. 

a. Broken. 

b. Grounded. 

3. Instrument. 

a. Dirty carburetor. 

b. Interrupter points on magneto. 

B. Carburetor. 

1. Water in carburetor. 

2. Dirt in the line. 



MOTORS. 343 



3. No pressure or no gas. 

4. Too lean a mixture. 
C. Engine. 

1. Cold. 

2. Valves sticking. 

II. Back Fires Through Carburetor: 

A. Ignition 

1. Wired wrong. 

2. Timed wrong. 

B. Carburetor. 

1. Water in carburetor. 

2. Dirt in line. 

3. No pressure or no gas. 

4. Too lean a mixture. 

C. Engine. 

1. Valve sticking (Inlet). 

III. Engine Knocks: 

A. Ignition. 

1. Retarded spark. Spark too far advanced. 

B. Engine. 

1. Carbonized cylinders (pre-ignition). 

2. Overheated engine. 

3. Loose bearings. 

4. Loose pistons. 

IV. Engine Lacks Power: 

A. Ignition. 

1. Retarded spark. 

B. Carburetor. 

1. Too rich a mixture. 

C. Engine. 

1. Exhaust valve not seating. 

2. Carbon in cylinder. 

3. Overheated engine. 

4. Lack of lubrication. 

5. Governor connections sticking. 

D. Brakes. 

1. Dragging. 

E. Clutch. 

1. Slipping. 



344 FIELD ARTILLERY MATERIEL. 

V. Engine Overheats. 

A. Ignition. 

1. Retarded spark. 

B. Carburetor. 

1. Rich mixture. 

C. Engine. 

1. Cooling system. 

a. Fan belt off. 

b. Xo water. 

c. No circulation. 

d. Anti-freezing mixture. 

2. Carbonized cylinder. 

3. Lack of lubrication. 

VI. Engine Stops: 

A. Engine and car stop gradually. 
1. Trouble with fuel. 

B. Engine and car stop suddenly. 
1. Mechanical trouble. 

C. Engine stops suddenly, car gradually. 
1. Trouble with ignition. 

VII. Engine Won't Stop: 

A. Ignition. 

1. Cable. 

2. Switch. 

B. Pre-ignition. 

1. Carbon in cylinders. 

2. Overheated engine. 

Consider how each of these indications may differ so 
that it is possible to locate the exact source of trouble without 
first investigating. If the car has been on the road for some 
time and the engine misses it will either miss regularly in one 
or more cylinders or irregularly in all cylinders. If the former, 
the miss is due to ignition. The cylinder in which the miss 
is occurring can be easily determined by short circuiting each 
plug with a screw driver. This is done by allowing the screw 
driver to touch the central electrode of the plug and also the 
engine. When a plug is short circuited and it does not affect 



MOTORS. 345 

the operation of the engine, it shows there was no spark 
jumping across the electrodes of the plug. If the cable to 
this plug is disconnected and held a short distance from the 
electrode of the plug from which it was removed, a spark will 
or will not jump this gap. If it does jump the gap it shows 
that the plug is short circuited. Then the plug is either car- 
bonized or the insulator is broken. If a spark does not occur 
place the cable near the engine and if a spark occurs it shows 
that the gap was too large at the electrodes of the plug. If 
no spark occurs it shows that the trouble is not in the plug 
but at some point ahead of this. If the engine is firing on all 
but one cylinder the trouble must be some place between the 
distributor rotor and the plug. First see if the distributor is 
dirty and then check up the cable to see if it is broken or 
grounded. One point to be remembered is that the parts of 
the magneto or the battery ignition system incorporated in the 
instruments will affect the operation on all the cylinders and 
there is no need of looking for the trouble there if only one 
cylinder misses. If every other cylinder to fire misses and 
magneto ignition is used, it is often due to the time lever 
housing being jammed over to one side so that the interrupter 
points are opened only by one cam. In no case is it necessary 
to file the interrupter points to overcome a miss, for the inter- 
rupter affects the operation on every cylinder and not on one. 

If the miss is irregular it is due to carburetor or to fuel 
trouble. To locate the trouble open the, pet cock at the bot- 
tom of the carburetor and if there is any water in the car- 
buretor it will run out. This operation also shows whether 
or not the gas runs freely. If it does not there may be dirt 
in the line or no gasoline supply. After everything else has 
been tried to overcome the trouble, adjust the carburetor to 
compensate for too lean a mixture. 

When an engine is first started it will often miss. This is 
due to the engine being cold. Under no circumstances should 



346 FIELD ARTILLERY MATERIEL. 

time be wasted to overcome missing until the engine is warm. 
If an exhaust valve sticks it will cause the engine to miss as 
the gases will be forced out on the compression stroke. This 
is difficult to locate as it is a regular miss but usually results 
from an overheated engine. 

If an engine backfires when first started and does so con- 
tinuously it is best to check up on the wiring and timing of the 
ignition system. If the engine is running smoothly and sud- 
denly starts to backfire through the carburetor it is possible 
that the magneto coupling has slipped. 

If there is water in the carburetor it may suddenly shut 
off the supply of gasoline and cause so lean a mixture that 
backfiring results. Dirt in the line or running out of gasoline 
would have the same effect. If backfiring in the carburetor is 
experienced in addition to the missing of the engine it is prob- 
ably due to too lean a mixture. Backfiring also results from 
the inlet valve sticking or not seating properly. 

If the engine suddenly develops a knock while in opera- 
tion it may be due to the ignition being too far advanced for 
the condition for which the car is operating and the spark 
lever should be retarded. This will be noticed mostly when 
the car is under a hard pull such as on hard hills or going 
through sandy roads. If the engine develops a knock, after 
having been run for a short while, which can not be overcome 
by retarding the spark it may be due to carbon in the cylinders 
or an overheated engine, both of which would cause pre-igni- 
tion of the charge. By pre-ignition is meant that the incom- 
ing charge when under compression is ignited due to the heat 
in the cylinder regardless of when the ignition spark takes 
place. Loose bearings and loose pistons will knock but these 
should be easily distinguished from ignition knocks as they 
are present at all times. 

If the engine shows a lack of power it may be that the 
ignition system is too far retarded due to the coupling driving 



MOTORS. 347 

of the magneto having slipped. If too rich a mixture is 
used it will cause a loss of power but can easily be distinguished 
by the black smoke which is given off at the exhaust pipe. 
Every precaution should be taken to locate the trouble when 
an engine shows a lack of power as it may be caused from 
the valve not seating properly, carbon in the cylinders, over- 
heated engine, lack of lubrication, or the governor connection 
sticking. If lack of lubrication is causing the trouble it will 
soon lead to mechanical trouble such as scoring the cylinder 
walls or burning out the bearings. An engine will often give 
an apparent indication of a lack of power due to the brakes 
dragging or the clutch slipping. 

If an engine overheats it is best to check up and see 
whether or not the car is being operated on a retarded spark 
or if the mixture is too rich. The usual trouble of the engine 
overheating are troubles experienced with the cooling system. 
Fan belts often break or slip, the water may have leaked out 
somewhere in the cooling system, or the circulation may be 
stopped up in some way. If anti-freezing mixtures are 
allowed to remain in the cooling system in warm weather they 
will cause overheating of the engine due to their low conduc- 
tivity of heat. Carbon in the cylinder causes the cylinder 
to overheat and is detrimental to its operation. If the en- 
gine is not lubricated properly it will overheat due to the ad- 
ditional friction of the parts. 

If after the car is in operation the car and engine slow down 
gradually the trouble is without doubt due to lack of fuel or 
some trouble with the fuel system or the carburetor. When 
the car stops under these conditions the engine usually back- 
fires into the carburetor just before thecar stops. 

If the car and the engine stop suddenly it is an indication 
of some mechanical trouble such as a frozen bearing, broken 
connecting rod, or some other part which suddenly puts a 
brake on the movement of the car. 



348 FIELD ARTILLERY MATERIEL. 

If the engine suddenly stops operating and the car con- 
tinues to coast the trouble can be traced to the ignition system. 
A disconnected or a broken wire usually causes the trouble. 

If the engine will not stop when the ignition switch is 
thrown to the "off" position it is possible with magneto igni- 
tion that the cable between the switch and the magneto is 
broken or disconnected. That is, the switch does not con- 
nect the primary of the magneto to the ground. If the engine 
is overheated, due to lack of proper cooling or carbon in the 
cylinders, the engine will continue to operate due to the pre- 
ignition. 



gunner's examinations. 349 



APPENDIX "A" 

GUNNERS' EXAMINATIONS. 

PREPARATION. 

In the preparation for the gunners' examination men 
should pay particular attention to the following points. 

Setting the Panoramic Sight. 

Before starting to use the panoramic sight,the peep sight 
should be turned as far as possible to the right or left. This 
should be done to make it easier for the gunner to look through 
the panoramic sight and also to prevent him from looking 
through the peep sight. 

Men should get in the habit of working from the top of 
the sight down, performing their duties always in the same 
order — this is very important. In other words in indirect 
laying he sets the deflection, applies the deflection difference, 
levels the cross level bubble and then lays for direction. In 
direct laying, he sets the deflection, sets the range, levels the 
cross level bubble, and lays the piece for direction and range. 
In setting the range on the sight shank the gunner should 
place his eye on a level with the index so that the range can be 
set exactly. If a range of over 500 yards is given, the fast 
motion of the scroll gear should be used. As soon as he has 
laid his gun he will call "Ready" and step clear of the piece. 
After he has called "Ready" under no circumstances will he 
attempt to finish any of his duties. If he does he will lose 
that trial. 

All scales should be set rapidly. In order to do this, men 
must not try to make any mathematical calculations. The 



350 FIELD ARTILLERY MATERIEL. 

setting of sights should be absolutely mechanical. The gun- 
ner should know exactly in what direction to turn the knobs, 
wheels and cranks in order to increase or decrease the settings 
and to move the bubbles in any particular direction. A list 
of reasons for disqualification are given in the Regulations 
for Gunners' Examination. 

It is most important in indirect laying that the gunner 
be assisted by TRAINED chiefs of sections and No. 2's. 
Men should be picked for this during the earlier part of the 
course and trained for that work. A great deal depends on 
the ability of these men. 

Setting the Peep Sight. 

In using the peep sight in direct laying the panoramic 
sight head should be turned to either flank so that there will 
be no chance of the gunners looking through the panoramic 
sight. The gunner in looking through the peep sight should 
keep his eye about six inches from it. 

Setting the Quadrant. 

Candidates should get in the habit of performing the 
required duties in the following order: (1) Setting the site 
with his right hand. (2) Setting the range with his left hand 
as prescribed for No. 1 (Instruction Memorandum No. 11 — 
5th hour, 1st week). (3) Centering the cross level bubble 
with his right hand. (4) Leveling the range bubble with his 
right hand. The candidate should be sure to look and see 
where the bubble is before he starts to turn the elevating 
crank handle. He should turn the handle quickly. After 
leveling the range bubble he calls "Set" and steps clear of the 
wheels. 

Fuse Setting. 

Candidates in setting the bracket fuze setter should stand 
immediately in rear of it and should crouch down. The cor- 



gunner's examinations. 351 

rector should be set first and the range next, both scales being 
set with the right hand. His assistant should stand im- 
mediately to the left and should pass the round to the can- 
didate who is being examined, as No. 5 passes the round to 
No. 4 in percussion fire. The candidate after setting the 
scales rises up, grasps the projectile and inserts it in the fuze 
setter. He then sets the fuze and calls "Ready." The assist- 
ant should hold the projectile so that the lug on the time ring- 
is at 10 o'clock (vertical clock face). The candidate when he 
inserts the round in the fuze setter should place it so that the 
lug on the time ring falls just to the left of the rotating pin 
notch. This is done so that the two shall engage as soon as 
possible. 

In setting the fuze with the hand fuze setter, the candi- 
date takes the position prescribed for No. 3 in the service of 
the piece, his assistant takes the position of No. 5 when the 
hand fuze setter is used. The candidate must be sure to press 
down on the hand fuze setter while setting the fuze. 

Candidates must be cautioned to remember all necessary 
data. They cannot ask the examining officer for any. It 
must be impressed on them also that under no circumstances 
can they start to set the scales before the instant prescribed 
by the Regulations for the Gunners' Examinations. 

Drill of the Gun Squad. 

Candidates should be familiar with the following para- 
graphs of the D. and S. R. F. A. : Formation of the gun squads 
(135, 138); to form the gun squad (170-173); to tell off the 
gun squad (174); post of the gun squads (175-177); to post 
the gun squad (178-179) ; post of the cannoneers, carriages 
limbered (180-182) ; to mount the cannoneers (183-185) ; to dis- 
mount the cannoneers (186-187); to change posts (189-190); 
to move by hand the carriages limbered (191-192); to leave 

T. B.— 23 



352 FIELD ARTILLERY MATERIEL. 

the park (204); action front (199); posts of the cannoneers, 
carriages unlimbered but not prepared for action (188) ; 
limber front and rear (202) ; action rear (200) ; limber rear 
(203); to move by hand the carriages unlimbered (937); pre- 
pare for action (938) ; march order (942) ; posts of the can- 
noneers, carriages unlimbered and prepared for action (941); 
duties in detail of the gunner (845-869) ; duties in detail No. 1 
(807-891); duties in detail of No. 2 (892-901); duties in detail 
of No. 3 (902-911); duties in detail of No. 4 (913-918); duties 
in detail of No. 5 (919-924) ; methods of laying (985-988) ; and 
methods of fire (995-1008). 

The questions will only cover the important points 
covered in the paragraphs above. 

Materiel. 

Candidates should be familiar with the following (Hand- 
book of the 3-inch Materiel): Nomenclature of harness and 
of the parts and accessories of the wheeled materiel; use of 
oils; method of cleaning and lubricating parts and mechanisms; 
method of cleaning cylinder oil and of emptying and filling 
cylinders; use of tools; the kinds of projectiles, of fuses, and 
of powder actually issued for use, and their general purpose 
and effect, omitting questions as to construction, weight, 
manufacture, and technical description; the care and preserva- 
tion of saddle and harness equipment in use. Description of: 
breech mechanism to dismount, to assemble, elevating screws, 
to dismount; to assemble; hub liner, to remove, to assemble; 
brakes, piece and caisson, to adjust; wheel, to remove, to 
replace. 

REGULATIONS FOR THE EXAMINATION OF GUNNERS. 

A record of marks will be kept during the examination, 
and at the conclusion thereof it will be submitted directly 



gunner's examinations. 353 

to the commander ordering the examination. The mark 
received by each man in each subject will appear opposite 
the man's name and the appropriate totals will be carried out. 
The tabular list, upon approval by the commander ordering 
the examination, will be published in orders. 

Men, to be classified as expert first class gunners, must 
attain an average of not less than 85% in each of the subjects 
which follow: to be classed as first class gunners, a general 
average of not less than 85% with an average in each subject 
of not less than 75%; to be classed as second class gunners, 
a general average of not less than 75%, with an average in 
each subject of not less than 65%. 

Examinations will include the following: 

Value of Subjects. 

Subject. Gun Batteries. 

Direct laying 24 

Indirect laying 24 

Laying for range 18 

Fuse setting 18 

Drill of the Gun Squad. 8 

Materiel 8 

The following general rules will govern the Examining 
Officers : 

1. The conditions of examination will be made, as nearly 
as possible, the same for all of the men. 

2. Setting of scales will be considered correct if any part 
of the index is coincident with any part of the line of the 
graduation of the setting ordered. 

3. Settings ordered will always be even divisions of the 
scale, and not fraction thereof. When a number greater than 
five is used, it will be a multiple of five, except in settings of the 
angle of site and corrector scales. 

4. The man may select any of the assistants authorized. 

5. The man is permitted to traverse the piece to the 
middle point of traverse before each trial at direct laying. 



354 FIELD ARTILLERY MATERIEL. 

6. The sight, quadrant, or fuse setter, etc., will be in 
the position in which it would be in service before the com- 
mand for trial with it is given;. the scales will be set at readings 
different from those to be given for the trial. 

7. The trials for direct laying will be with different de- 
flections and ranges; for indirect laying with different deflec- 
tions and deflection differences; for laying for range, with 
different angles of site and ranges. The trail w'll be shifted 
in three trials at direct laying. 

8. Changes in setting of scales required of men will not 
exceed the following: Deflection scale of peep sight, 15 mils; 
of panoramic sight, 200 mils; deflection difference scale, 30 
mils; corrector scale, 10 mils; angle of site scale, 10 mils; 
range scales, 800 yards. At direct laying the deflections an- 
nounced will be between 6370 and 30. At direct laying the 
cross level of the tangent sight will be thrown out of level by 
the examiner for the trials requiring shifting of the trail. 

In time trials, time will be taken from the word at which 
the candidate is instructed by this order to commence his 
trial to the candidate's "Ready," or to the last word of any 
announcement required. No credits will be allowed if the 
candidate performs any part of the trial after this interval 
or if the time taken exceeds the maximum given in the appro- 
propriate table of those shown hereinafter. 

Should any trial be vitiated through the fault of an ex- 
aminer, of an assistant, of the sight or other instrument used, 
that trial will be void and the candidate will be given imme- 
diately another trial of the same nature. 

Direct Laying. 

12 trials: Six with the peep sight and six with the pano- 
ramic sight. 



gunner's examinations. 355 

The target will represent a shielded gun and caisson and 
will be placed, as nearly as practicable, at a distance of 1,000 
yards from the gun used in the trials. 

The candidate being seated on the gunner's seat, an 
officer of the battery commands, for example: 

1. Target, that gun. 

2. Deflection, 10. 

3. 2400. 

At the indication of the target, the candidate causes an 
assistant at the trail to point the piece in its general direction; 
at the last word of the last command he sets off the deflection 
and the range ordered; corrects for difference of level of the 
wheels; operates the elevating and traversing apparatus so 
as to bring the line of sight upon the target; calls "Ready," 
and steps clear. 

No credits will be given in the following cases: 

(1) If the sight is incorrectly set for deflection or range. 

(2) If, when the bubble of the cross level is accurately 
centered, the line of sight is found not to be on any portion 
of the target. 

If the piece is found to be correctly laid within the limits 
prescribed, credits will be given as follows 

Time in seconds, exactly, 

or less than 16 18 20 21 22 23 



Credits 2.0 1.9 1.7 1.5 1.4 1.3 

Indirect Laying. 

12 trials. 

Two aiming points will be selected, one toward the front 
and one toward the rear. They should be of the type used in 
actual firing and, for the purpose of this examination, should 
be about 2 mils in width, well defined, of such height as 



356 FIELD ARTILLERY MATERIEL. 

readily to be brought within the field of view, and about 1500 
yards distant. They should be clearly pointed out to the 
candidates. 

All of the guns of the battery will be placed in the order 
in battery and a candidate will be assigned to each. 

For all trials the board will assume a situation in the con- 
duct of fire for adjustment by battery, commencing with the 
first salvo, that will require commands involving a shift of 
the trail for this first trial, and, for all trials, such deflection 
and deflection difference settings and changes of settings of 
scales, not exceeding the limits prescribed in paragraph 5 
of this order, as may reasonably be expected in service. 

When the aiming point is in rear the candidate will be 
allowed an assistant who, from a position in front of the axle, 
signals to a man at the end of the trail to move it, if neces- 
sary, so as to bring the aiming point within the field of view 
of the sight. When the aiming point is in front, an assistant 
at the end of the trail is allowed. 

The candidates being seated on the gunners' seats, an 
officer of the battery commands, for example: 

1. Aiming point, the chimney on that white house. 

2. Deflection, 440. 

3. On No. 2 close 10. 

At the last word of command for the deflection each man 
sets off the deflection; applies the correction for deflection 
difference appropriate for his piece; causes the trail to be 
shifted until the sight is directed upon the aiming point; cor- 
rects for difference of level of the wheels; raises or lowers the 
panoramic sight until the field of view will include the aiming 
point; traverses the piece until the vertical hair is on the aim- 
ing point; calls "Ready" and steps clear. 

The trial being completed and the men again being seated, 
the officer commands for example, in continuance of the as- 
sumed situation: 



gunner's examinations. 357 

1. Right, 120. 

2. On No. 4, close 5. 

At the last word of command for the deflection, each man 
operates the sight and, if necessary, the trail as before; tra- 
verses the piece until the vertical hair is on the aiming point; 
calls "Ready" and steps clear. 

The third and fourth trial is similarly conducted. 

No credits will be given in the following cases: 

1. If the sight is incorrectly set for the deflection or 
deflection difference. 

2. If, when the bubble of the cross level is accurately 
centered, the vertical cross hair is found not to be on the aim- 
ing point. 

3. If, at any time during the trial, the man has operated 
the elevating device. 

If the piece is found to be correctly laid within the limits 
prescribed, credits will be given as follows: 

Time in seconds, exactly, 

or less than 18 20 21 22 23 24 



Credits 2.0 1.9 1.7 1.5 1.4 1.3 

Laying for Range. 

Six trials, using the range quadrant. 
The man being seated on the seat on the right side of 
the trail, an officer of the battery commands, for examp'e: 

1. Site, 280. 

2. 3400. 

At the last word of the command, the man sets off the 
angle of site; sets the quadrant for range; corrects for difference 
of level of wheels; turns the elevating crank so as to center 
the range bubble; calls "Ready" and steps clear. 

No credits will be given in the following cases : 



358 FIELD ARTILLERY MATERIEL. 

1. If the quadrant is incorrectly set for angle of site or 
range. 

2. If no part of the bubble of the cross level is between 
the middle two lines on the glass tube. 

3. If there be found to be an error of more than 50 yards 
in laying for any range less than 1,500 yards or more than 25 
yards for any equal range to or exceeding 1,500 yards. 

If the piece is found to be correctly laid within the limits 
prescribed, credits will be given as follows: 

Time in seconds, exactly 

or less than 14 16 18 19 20 21 



Credits 3.0 2.3 2.6 2.4 2.2 2 

Fuse Setting. 

12 Trials: 6 with the bracket fuse setter, 6 with the hand 
fuse setter. 

Drill cartridges with fuses in good order set at safety are 
placed as in service. An officer of the battery commands, for 
example : 

1. Corrector, 24. 

2. 2700. 

At the last word of the command for the corrector, in 
trials with the bracket fuse setter, the man sets the fuse setter 
at the corrector, and, as the data are received, at the range 
ordered, receives the cartridge from an assistant, inserts its 
head in the instrument, sets the fuse and calls "Ready." 

At the last word of the command for the corrector, in 
trials with the hand fuse setter, the candidate sets the fuse 
setter at the corrector, and, as the data are received at the 
range, ordered; with the aid of an assistant, sets the fuse, 
and calls "Ready." 

No credits are given in the following cases: 



gunner's examinations. 359 

1. If the fuse setter is incorrectly set for corrector or 
range. 

2. If the candidate fails to obtain a correct fuse setting 
within one-fifth of a second. 

If the fuse setter is found to be correctly set and is properly 
operated, credits are given as follows: 

Time in seconds, exactly 

or less than 8 9 10 11 12 13 



Credits 1.5 1.4 1.3 1.2 1.1 1.0 

Drill of the Gun Squad. 

The subjects will embrace such parts of the following 
exercises (D. and S. R. F. A.) as will thoroughly test the can- 
didate's familiarity with the service of the piece: Formation of 
the gun squad (135, 138); to form the gun squad (170-173); 
to tell off the gun squad (174); post of the gun squads (175- 
177) ; to post the gun squad (178-179) ; posts of the cannoneers, 
carriages limbered (180-182); to mount the cannoneers (183- 
185); to dismount the cannoneers (186-187); to change posts 
(189-190); to move by hand the carriages limbered (191-192); 
to leave the park (204); action front (199); posts of the can- 
noneers, carriages unlimbered but not prepared for action 
(188); limber front and rear (202); action rear (200): limber 
rear (203) ; to move by hand the carriages unlimbered (937) ; 
prepare for action (938); march order (942); posts of the 
cannoneers, carriages unlimbered and prepared for action 
(941); duties in detail of the gunner (845-869); duties in de- 
tail of No. 1 (870-891); duties in detail of No. 2 (892-901); 
duties in detail of No. 3 (902-911); duties in detail of No. 4 
(913-918); duties in detail of No. 5 (919-924); methods of 
laying (985-988); and methods of fire (995-1008). 

The questions will only cover the important parts covered 
in the paragraphs above. 



360 FIELD ARTILLERY MATERIEL. 



Materiel. 

The examination of each candidate will be sufficiently 
extended to test his familiarity with the use and care of the 
materiel of his organization, and will be theoretical. The 
examination will be conducted by questions on the following 
subjects: Nomenclature of harness and of the parts and ac- 
cessories of the wheeled materiel; use of oils; method of clean- 
ing and lubricating parts and mechanisms; method of cleaning 
cylinder oil and of emptying and filling cylinders; use of tools; 
the kinds of projectiles, of fuses, and of powder actually issued 
for use, and their projectiles, of fuses, and of powder actually 
issued for use, and their general purpose and effect, omitting 
questions as to construction, weight, manufacture, and tech- 
nical description; the care and preservation of saddle and har- 
ness equipment in use. Description of: breech mechanism, 
to mount, to assemble; elevating screws, to dismount, to 
assemble; hub liner, to remove, to assemble; brakes, piece and 
caisson, to adjust; wheel, to remove, to replace. 

Chevrons will be issued to those candidates who qualify 
and will be worn as prescribed in orders. 

DONT'S FOR CANNONEERS. 

Don'ts for All Cannoneers: 

— Sacrifice accuracy for speed. 

—Guess at the data. 

— Expose yourself. 

— Let your attention be distracted. 

— Make unnecessary moves. 

—Talk. 

Dont's for Chief of Section: 

— Forget that you are responsible for the work of your squad. 
— Fail to assist the gunner in laying on the aiming point. 
— Say "Muzzle Right (left)," merely move your hand in the direc- 
tion you desire the traikshifted. 



gunner's examinations. 361 

— Write down the data. 

— Forget your proper pose, covering No. 3 opposite the float. 

— Forget to extend your arm vertically, fingers joined, after the 
gunner has announced "Ready." 

— Fail to caution "With the Lanyard" for the first shot. 

— Fail to look at both gunner and executive. 

— Command "Fire;" merely drop your arm. 

— Fail to designate who shall assist No. 2 when he is unable to 
shift the trail. 

— Forget to announce "Volley Complete." 

— Forget to select the individual Aiming Points for the gunner. 

— Forget to announce "No. (so & so) on Aiming Point," in re- 
ciprocal laying. 

—Ever say "Range 3000," merely "3000." 

Dont's for Gunner : 

— Forget to place the sight bracket cover in the left axle seat. 

— Forget to put the sight shank cover in the trail box. 

— Forget to close the panoramic sight box, and fasten it with your 

left hand. 
— Forget to clamp the panoramic sight in its seat. 
— Forget to close the ports in the shield. 
— Forget to put your weight against the shoulder guard while 

laying. 
— Touch any adjustment after calling "Ready." 
— Forget to move your head from the panoramic sight after calling 

"Ready." 
— Lean against the wheel. 

— Fail to take up lost motion in the proper direction. 
— Fail to watch the executive after calling "Ready." 
— Signal with your hand for movements of the trail. 
— Fail to identify Aiming Points or Targets. 
— Fail to secure hood on sight bracket. 
■ — Say "Whoa" to No. 2 while the trail is being shifted. Say 

"Trail Down." 
— Fail to lower the top shield at once at the command "March 

Order." 
■ — Forget to re-lay vertical hair on A. P. at completion of sweeping 

voley. 
— Forget to set range 1000, deflection zero in "Fire at Will." 



362 FIELD ARTILLERY MATERIEL. 

— Forget to say "Ready" just loud enough for the chief of section 

to hear. 
— Forget to chalk up the deflection on the main shield in reciprocal 

laying. 
— Forget to set site and level bubble (British). 
— Forget to release the brake in trail shifts (British). 
— Forget to count "1001, 1002" to preserve proper firing interval. 

Dont's for Number 1: 

— Touch the firing handle until you announce "Set." 

— Fire the piece with the right hand. 

— Try to throw the drill cartridge over the float by jerking the 

breech open. 
— Slam the breech. 
— Fail to level bubbles. 

— Fail to set and release brake in trail shifts. 
— Fail to look squarely at the scales of the quadrant. 
— Fail to take up lost motion properly. 
— Forget to close the quadrant box. 
— Fire the piece until the command is given. 
— Lean against the wheel. 

— Forget to keep up with the range in direct laying. 
— Forget to lower the top shield immediately at "March Order." 
—Talk. 

Dont's for Number 2: 

— Throw the breech cover on the ground. 

— Fail to engage the hand-spike. 

— Slam the apron. 

— Put feet on the float. 

— Wait for the command in shifts of 50 mils or more. 

— Move the trail in a series of shifts. 

— Fail to mark off 11 lines 50 mils apart at once on taking your 

post. 
— Fail to secure the breech cover. 
— Fail to secure the hand-spike in "March Order." 
— Run between carriages. 
— Fail to throw empty cartridge cases out of the way of the 

cannoneers. 
— Forget the tow and waste. 
—Talk. 



gunner's examinations. 363 

Dont's for Number 3: 

—Run between the carriages. 

— Throw the muzzle cover on the ground. 

— Throw the front sight cover on the ground. 

— Slam the apron. 

— Fail to see that fuze is set at safety at "March Order." 

— Fail to look directly down at the fuze setter while adjusting 

scales. 
— Take right hand from the corrector worm knob and left from 

the range worm crank, during drill. 
— Forget to set range zero in "Fire at Will." 
— Cross your legs. 
— Forget to set each announced range regardless of the kind of 

fire being used. 
—Talk. 

Dont's for Number 4 : 

— Throw the fuze setter cover on the ground. 

— Slam the apron. 

— Forget to set the fuze at "Safety" in "March Order." 

— Fail to glance into the bore to get the alignment. 

— Touch a round after inserting it in the breech. 

— Fail to completely set each fuze. 

— Forget to take the round from No. 5 from beneath in percussion 

fire and from the top when the hand fuze setter is used. 
— Forget to say, "3200, 2, last round," only loud enough to reach 

the chief of section. 
— Forget to secure the cover on the fuze setter. 
— Attempt to move the caisson with the door open. 
— Forget to set and release the caisson brake (Model 1902). 
— Turn the round to the left after setting. 
—Talk. 

Dont's for Number 5: 

— Slam the apron. 

— Attempt to move the caisson with the door open. 

— Forget to put your left elbow on the outside of your left knee 

in using the hand fuze setter. 
— Forget to set the brake on the 1916 caisson. 
— Throw the water-proof caps under your feet. 
—Talk. 



364 FIELD ARTILLERY MATERIEL. 



TRAINING GUN CREWS. 

This article is not intended to cover all of the work of 
the gun crew, it is intended merely to cover certain points 
sometimes lost sight of. References are to the 3" gun, but 
any crew efficient in serving that excellent weapon will 
have little trouble in mastering any other. 

All refinements taught have but one prime object, that is 
accuracy of fire. It is of no value to make atmospheric and 
velocity corrections if still greater variations are constantly 
introduced by poor service of the piece. The foundation of 
battery efficiency is well-trained gun crews. Officers may be 
able to lay out orienting lines with the greatest facility, may 
know the range tables in the dark, but it will avail little if they 
cannot train men to apply properly and accurately the data 
determined. 

The safety of our own infantry and the effectiveness of 
our fire are absolutely dependent on the continuous training 
of gun crews, and the resultant precision and sureness with 
which they perform their work. This can only be obtained 
by constant drill from the day the recruit joins until the day 
of his discharge; not by long drills in which he grows tried 
and loses interest, but by short periods broken by instruction 
in other subjects; not by many hours one week and none the 
next, but by a short period every day of the week. The 
best gunners grow rusty in a very few days; constant short 
drills will give results and are the secret of success. Every 
man must get instructions every day, be he raw recruit or 
expert gunner. 

Cannoneers should be taught that the greatest crime that 
can be committed in laying the piece is to make an error — 
the only crime for which there is no punishment. An error 
or mistake in the correct service of the piece should not be 
punished, but it should be carefully explained how the ef- 



gunner's examinations. 365 

ficiency of the battery depends on each member, and to insure 
that crime is not committed again, additional hours of in- 
struction beyond that required for the rest of the crew will be 
necessary. 

Every man must be on his toes from the time he comes in 
sight of his gun, every movement at the piece must be at a 
run. Slow and sleepy motions of one man will kill all the 
snap and energy of every other member of the crew. Do not, 
however, confuse speed of performing any given motion with 
hurry in execution of detail. For example, the gunner must 
move with snap and energy in getting his eye back to the sight 
and his hand on the traversing handwheel after the piece is 
fired, but he must never be hurried in getting the vertical 
wire exactly on the aiming point, or in making the ordered 
changes in the deflection setting. Stop watches should not 
be used. They are a fruitful cause of errors. Speed comes 
from continual practice and it cannot be artificially attained 
by stop-watch timing. Do not understand that speed is not 
desirable, it is highly desirable, but practice alone will give 
it and it will nearly always be found that the best-trained 
crew is the fastest crew. Competitions between crews must 
be for accuracy, not speed. If every motion is made with 
a snap and at a run the results as regards speed will be satis- 
factory. 

The accuracy of fire is affected by brakes not being ad- 
justed for equal tension, by direction of recoil not being in line 
with the trail, by No. 2 sitting on the handspike and shifting 
his weight after the gunner has called "Ready;" by No. 1 
jerking the firing handle; by the gunner not keeping his 
shoulder against the guard; by elevating cranks not being 
properly assembled ; by sights and quadrants not being prop- 
erly adjusted or locked with means provided (this subject 
deserves several pages) ; by variations in the amount of oil 
in the cylinder; by improper adjustment of the gland; by the 



366 FIELD ARTILLERY MATERIEL. 

gunner coming on to the aiming point sometimes from the 
right, sometimes from the left; by the No. 1 centering the 
bubble sometimes from front to rear, sometimes from rear 
to front. 

You may have stood behind a battery firing and noticed 
how one or two guns jump violently in recoil, while others 
would hardly disturb the proverbial glass of water on top of 
the wheel, although all guns of equal service. This was due 
almost entirely to the lack of proper adjustment of some of 
the parts mentioned above. 

Every member of the crew must know his duties so well 
as to make his motion automatic; the direction to turn the 
various handwheels, milled heads, and gears to obtain the 
desired result, and he must always do these things in the same 
way. The effect of small differences in laying may be graph- 
ically shown the gun crew by firing sub-caliber ammunition 
at a small arms steel target which rings a bell when a bull's- 
eye is made. Erratic shots means poor adjustments of 
equipment or poor training of the gun crew. Pleas that 
worn material or lost motion, or defective ammunition are the 
causes of erratic shooting are largely excuses for ignorance, 
laziness, and lack of proper instruction. Worn materiel re- 
quires more makeshifts, takes longer to lay and more careful 
watching, so that fire cannot be so rapid, but except for wear 
in the bore of the gun it is possible to do almost as accurate 
shooting with worn materiel, especially if the new materiel 
has not been thoroughly worked in. 

Among the more important duties of the men may be 
mentioned in the following: 

Chief of Section. — Must teach his men to have pride in 
the gun they serve, and the reputation of the section. He 
shows each member how the accuracy of firing is dependent 
on him, and that one man may ruin the best efforts of all the 
others. He must keep his materiel as clean as when it left 



gunner's examinations. 367 

the makers hand, every part functioning properly, every screw 
and nut tightened, no burred nuts or bolts, or missing split 
pins. He helps each member to take a pride in keeping the 
part for which he is responsible as clean as a new pin and in 
perfect condition. He sees that the various canvas covers 
and sponge and rammer never touch the ground where they 
will gather dirt. He knows the proper use of his tools, and 
the correct adjustment of the firing mechanism. He must be 
able to assemble and disassemble blindfolded the firing lock 
and breach mechanism. In firing he knows the settings of 
all scales without reference to a data book. 

The Gunner. — Knows. that turning the levelling screw 
clockwise moves cross bubble to the right; that turning scroll 
gear clockwise increases the range; that turning the peep sight 
screw clockwise increases deflection, and so on with all hand- 
wheels, etc., that he operates and must know these things "so 
well that he operates them in the proper direction automat- 
ically. Must always bring vertical wire on aiming point 
from the left to take up any play in traversing mechanism. 
He verifies that he is on the aiming point after the breech is 
closed and if there is any delay, again immediately before 
firing. He gets his eye back to the sight and relays imme- 
diately the gun returns to battery. He knows his scale read- 
ings at all times. He keeps his sight scrupulously clean, 
never permits his finger to touch the objective prism when 
turning the rotating head, nor wipes off eye piece with hand. 
He keeps his shoulder against the guard at all times. 

The Number 1. — He knows his site and range scale read- 
ings without having to look at them. In centering the bubble 
he brings it always from front to rear to take up play in the 
elevating mechanism. He centres the bubble so accurately 
that it is not the thickness of a sheet of tissue paper nearer 
one graduation than the other, and what is most important 
he sees that it stays there until he fires the pieces, when he 



368 FIELD ARTILLERY MATERIEL. 

promptly recentres it. (The latitude allowed in centring 
the bubble by our gunners' examination is responsible for 
20 per cent, of our field probable error.) He must not fire 
the piece with a jerk but with a constant even pressure, else 
he may destroy all his accuracy of levelling. The same 
principle applies if he uses the lanyard. He keeps his quad- 
rant free from any sign of dirt and assures himself that it is 
in perfect condition. If the gunner fails to keep his shoulder 
against the guard when the piece is fired he reminds him of it. 
In centring the bubble or setting the scales he gets his eye 
squarely opposite the scale or bubble. 

The Number 2. — He knows the width of the spade, float, 
etc., in mils, and is able to make any shift under two hundred 
mils, within 5 mils. He shifts the trail so as to bring the direc- 
tion of recoil in line with it (except for moving targets). In 
receiving empty cases he should not permit them to strike the 
trail or throw them against each other, as they must then be 
resized before they can be again used. If he sits on the hand- 
spike he must not shift his weight after the piece is laid. 

The Number 3. — He knows that turning the corrector 
worm knob clockwise decreases the setting; turning the range 
worm crank clockwise increases the range. In making these 
settings he keeps his eye squarely over the scales. He knows 
his scale settings at all times. He is taught to keep his fuze 
setter and its cover clean, and is shown how a small pile of 
dirt or wax behind the stop pin or in the rotating pin notch 
can throw out his settings and ruin the reputation of his sec- 
tion. Gum from the fuze often collects in these places. The 
surest way is to keep a match stick handy and clean out these 
places whenever there is a lull in the firing. 

The Number 4. — If necessary to reset the fuze he must 
turn the projectile until it brings up against the stop pin, then 
cease all turning movement and draw the projectile straight 
out of the fuze setter. If he continues the turning motion 

T. B.— 24 



gunner's examinations. 369 

unconsciously he can easily alter the setting by a fifth of a 
second. In loading he is careful not to strike the fuze against 
the breech and so alter the fuze setting. 

The Number 5. — He knows where the rotating pin notch 
is in the fuze setter, and where the corresponding pin is on 
the fuze. He places the fuze so that the pin is seated in the 
notch with little or no turning movement and turns rapidly 
but with no more force than required. He is careful to set all 
fuzes with the same force, that is, not turn one with a violent 
twist and the next barely up to the stop. 



370 



FIELD ARTILLERY MATERIEL. 



U. States, 1916. 



U. States, 1902. 



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gunners' examinations. 371 



'APPENDIX "C 



un» 



TABLE OF EQUIVALENTS. 

1 mil 3.37 minutes. 

1 meter (m) 39.37 inches. 

1 centimeter (cm) 3937 inch. 

1 millimeter (mm) .03937 inch. 

1 kilogram (kg) 2.2046 pounds. 

1 dekagram (dkg) .3527 ounce. 

1 gram 15.432 grains. 

1 liter 1.05671 quarts (U.S.). 

1 inch 2.54 centimeters. 

1 foot 3048 meter. 

1 yard .9144 meter. 

1 square inch 6.452 square centi- 
meters. 

1 cubic inch 16.39 cubic centimeters. 

1 cubic foot 02832 cubic meter. 

1 cubic yard 7645 cubic meter. 

1 ounce 28.35 grams. 

1 pound 4536 kilogram. 

1 quart (U. S.) 9463 liter. 

1 degree 17.777 mils. 

1 kilogram (kg) per square centi- 
meter 14.223 pounds per square 

inch. 



INDEX. 



INDEX 

Page. 

Abatage, French 75-mm 95 

Action of Recoil Mechanism, 3-inch Gun 70 

Aiming Circle 274 

Air and Liquid Pumps, 155-mm Howitzer 189 

American 75 105 

Ammunition 199 

Ammunition 3-inch Gun 214 

Ammunition, Definition of 11 

Ammunition Marking 233 

Ammunition Truck 334 

Angle of Site Mechanism, American 75 127 

Anti-Aircraft Guns 60 

Armament, Modern 46 

Army Artillery 57 

Artillery, Definition of 11 

Artillery Tractor 330 

Assembling 3-inch Gun 76, 242 

Assembling American 75 133 

Automatic Pistol 315 

Automatic Rifle 322 , 325 

Axles, Discussion 44 

Ballistics, Definition of 11 

Battery Commander's Telescope Model 1915 270 

Bibical References to Artillery 16 

Bicarbonate of Soda 239 

Bore, Definition of 11 

Borax 238 

Bracket, Fuze Setter 283 

Breechblock, 4.7-inch Gun 156 

Breechblock, British 75 150 

Breechblock, French 75 87 

Breechblocks, Discussion of 31 

Breech, Definition of 12 

Breech Mechanism 3-inch Gun 63 



II INDEX. 

Page. 

Breech Mechanism, American 75 106 

Breech Mechanism, G. P. F 162 

Breech Mechanism, 155-mm Howitzer 173 

British 75 147 

Browning Automatic Rifle 325 

Browning Machine Gun 323 

Built-up Guns, Discussion of 29 

Caisson 3-inch Gun 74 

Caisson, Definition of 12 

Caliber, Definition of 12 

Camp Telephone 286 

Canvas Buckets 241 

Care of 3-inch Gun 242 

Care and Cleaning of Cloth 252 

Care and Cleaning of Leather 249 

Care and Cleaning of Metal 252 

Care and Inspection of Sights 267 

Care and Preservation, French 75 101 

Care of Guns During Firing 253 

Care of 155-mm Howitzer, Notes on 194 

Care and Preservation of Materiel 236 

Carriages, Gun, 3-inch 65 

Carriage, Gun, Definition of 12 

Carriage, American 75, Description Ill 

Carriage 4.7-inch Gun, Description 154 

Carriage 155-mm Howitzer, Description 179 

Cartridge Case, Care of 219 

Cartridge, Case, Definition 12 

Charge, Definition 12 

Classification of fuzes 224 

Cleaning Material 236 

Cleaning Schedule 254 

Clock Oil, Use of 237 

Cloth Equipment, Care of 252 

Coal Oil, Use of 237 

Combination Fuzes, Tables of 232 

Cannoneers' "Don'ts" 360 

Conventional Signals 301 

Corps Artillery, Discussion 55 



INDEX. Ill 

Page. 

Cradle, Definition of 12 

Cradle, American 75, Description 118 

Cradle, G. P. F. Description , 162 

Cradle 155-mm Howitzer, Description 181 

Cradle 3-inch Gun, Description 66 

Cylinders 3-inch Gun, Care of 244 

Cylinders 155-mm Howitzer, Description 181 

Cylinders, Outer, Discussion 31 

Detonating Fuzes, Tables of 229 

Detonaters, Discussion 199 

Dismounting American 75 133 

Dismounting French 75 101 

Dismounting 3-inch Gun 76 

Divisional Artillery 47 

"Dont's" for Cannoneers 363 

Elevating Gear, 3-inch Gun 66 

Elevating Mechanism, American 75 129 

Elevating Mechanism, British 75 150 

Elevating Mechanism, Definition 13 

Elevating Mechanisms, Discussion 37 

Elevating Mechanism 4.7-inch Gun 157 

Elevating Mechanism, 155-mm Howitzer 185 

Engine Oils, Use of 238 

Engine Troubles, Motors 345 

Equalizing Gear, American 75 127 

Equivalents, Tables of 374 

Explosives, Discussion 199 

Extractor, French 75 87 

Faults, Common in Telephones 297 

Field Glasses 283 

Filling American 75 Cylinders 145 

Filloux 155-mm Gun 160 

Fire Control Equipment, Definition 13 

Fire Control Instruments 260 

Firing Mechanism, American 75 110 

Firing Mechanism, French 75 89 

Firing Mechanism, Definition 13 



IV INDEX. 

Page. 

Firing Mechanism, 4.7-inch Gun 156 

Firing Mechanism, 3-inch Gun 64 

Firing Mechanism, 155-mm Howitzer 175 

Fireworks, Signalling 304 

Fixed Ammunition 203 

Flags, Signalling 285 

Floats, American 75 114 

French 75 84 

Front and Rear Sights, 3-inch Gun 260 

Fulminates 199 

Fuzes 221 

Fuze Classification 224 

Fuze, Definition 13 

Fuze Setter, 3-inch Gun 283 

Fuze Setters, Definition 13 

General Service Code 301 

Gribeauval, Reference to 20 

G. P. F. (Grande Puissance Filloux) 160 

Gun, Definition 13 

Gun Crews, Training of 367 

Gun Carriages, Discussion 33 

Gun Carriage, 3-inch Gun 65 

Gunners Examinations 352 

Guns, Care of in Firing 254 

Guns Used in World War 370 

Gustavus Adolphus, Reference to 18 

H and H Soap, Use of 239 

Hand Fuze Setter 284 

Heavy Field Gun, Discussion 58 

Heavy Field Howitzer, Discussion 59 

High Explosives 202 

History and Development of Materiel 16 

Hollingshead Soap, Use of 239 

How to Drive Motors 340 

Howitzers, 155-mm, Care of 194 

Howitzer, 155-mm, Model 1918 167 

Howitzer, Definition of 13 

Hydroline Oil, Use of 239 



INDEX. V 

Page. 

Independent Angle of Site Ill 

Initial Velocity, Definition of 13 

Lamps, Signalling 298 

Lanterns 242 

Lavaline, Use of 238 

Leather, Care of 249 

Light Gun and Howitzer, Discussion 48 

Light Slushing Oil, Use of 237 

Limber, Definition of 14 

Limber, 3-inch Gun (Caisson) 72 

Line Sights 258 

Louis XIV, Reference to 20 

Liquid Pumps for 155-mm Howitzer 189 

Lubricating Oil, Use of 236 

Lye Powdered, Use of 238 

Machine Gun, Browning 324 

Machine Guns, Use of 321 

Marks on Ammunition 233 

Materiel, Definition of 14 

Medium Gun and Howitzer 55 

Metal, Care of 252 

Modern Armament Discussion 46 

Monocord Switchboard 288 

Motors , 328 

Mortar, Definition of 14 

Motorization 50 

Muzzle, Definition of 14 

Muzzle Velocity, Definition of 14 

Naphthaline, use of 238 

Neats-foot Oil, Use of 237 

Nitrogen Compounds 203 

Observing Instruments 270 

Obturation 204 

Ogive, Definition of 14 

Ordnance, Definition of 14 

Outer Cylinders, Discussion of 31 



VI INDEX. 

Page. 

Paint, Rubberine 238 

Panels, Signalling 305 

Panoramic Sight, Model 1917 260 

Panoramic Sight, Model 1915 263 

Paulins 242 

Percussion Primers 208 

Petrolatum .' 237 

Picket Ropes 242 

Peice, Definition of 14 

Pistol, Automatic 315 

Polish, Gibsons Soap 238 

Powder Bags 206 

Preparation for Gunners Examinations 349 

Pressure Gauge, 155-mm Howitzer 192 

Primers 206 

Primer, Brown Enamel 238 

Primer, Definition of 14 

Primer, Pressing 208 

Projectile, Definition of 14 

Projectile, Shape and Nomenclature 209 

Projectors, Signalling 298 

Propelling Charges 201 

Pumps, Air and Liquid 189 

Quadrant, Gunners, Definition of 14 

Quadrant, Range 3-inch Gun 265 

Quadrant, Sight 155-mm Howitzer 192 

Radio, SCR 54 and 54a 307 

Railway Artillery, Discussion 60 

Range Finder . . . . 4 278 

Range Quadrant 3-inch Gun 265 

Recoil Mechanism, Definition of 14 

Recoil Mechanism, Discussion 39 

Recoil Mechanism, 3-inch Gun 68 

Recoil Mechanism, American 75 120 

Recoil Mechanism, British 75 150 

Recoil Mechanism, French 75 99 

Recoil Mechanism, 4.7-inch Gun 156 

Recoil Mechanism, G. P. F 162 



INDEX. VII 

Page. 

Recoil Mechanism, 155-mm Howitzer , 182 

Reconnaissance Car 328 

Regulations for Gunners' Examinations 352 

Rifle, Definitions of 14 

Rifling, Definition of 15 

Rounds, Definition of 15 

Runners 285 

Sal Soda 239 

Schedule, Cleaning 254 

Semi-fixed Ammunition 204 

Semaphore 306 

Separate Ammunition 204 

Shell, Definition of 15 

Shell Fillers , . 201 

Shields, Discussion of 43 

Shrapnel, Definition of 15 

Sights ' 258 

Sights, Care of and Inspection 267 

Sights, Discussion of 43 

Sights, Front and Rear 258 

Sights, Line 258 

Sights, Panoramic 260 

Signals, Conventional 301 

Signal Equipment 285 

Small Arms 315 

Soap H and H 239 

Soap, Castile 239 

Soap, Saddle 239 

Spades, American 75-mm 114 

Spare Parts 3-inch Gun 240 

Sperm Oil, Use of 237 

Swabbing Solution 239 

Switchboard, Monocord 288 

Table of Equivalents 371 

Table of Explosives 202 

Table of Fuzes 232 

Telephone, Camp 286 

Telephone Faults 295 



VIII INDEX. 

Page. 

Telescope, B. C. Models, 1915 and 1917 270 

Tools and Accessories 3-inch Gun 239 

Training Gun Crews 364 

Trail, 3-inch Gun 66 

Trail, American 75 1 14 

Trail, British 75 150 

Trail, 4.7-inch Gun 157 

Trail, G. P. F. Gun 165 

Trails, Definition of 15 

Trails, Discussion of 45 

Traversing Mechanism 3-inch Gun 66 

Traversing Mechanism, American 75 133 

Traversing Mechanism, British 75 153 

Traversing Mechanism, 4.7-inch Gun 156 

Traversing Mechanism, G. P. F 165 

Traversing Mechanism, 155 Howitzer 187 

Traversing Mechanism, Definition of 15 

Traversing Mechanisms, Discussion of 36 

Tubes, Discussion of 27 

Twist, Discussion of 29 

Type SCR 54 and 54a Radio 307 

Vacuum Tube Detector 311 

Vaseline 237 

Variable Recoil, American 75 126 

Weights and Dimensions 3-inch Gun 62 

Weights and Dimensions 4.7-inch Gun 154 

Weights and Dimensions American 75 105 

Weights and Dimensions British 75 147 

Wheels, Care of 248 

Wheels, Discussions of 44 

Wheels, 3-inch Gun 65 

Wheels, 4.7-inch Gun 157 

Wheels, G. P. F 165 

Wig- Wag 306 

Wire- Wrapped Guns, Discussion 28 

V 



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